U.S. patent number 5,909,081 [Application Number 08/875,756] was granted by the patent office on 1999-06-01 for multi-color light emission apparatus with organic electroluminescent device.
This patent grant is currently assigned to Idemitsu Kosan Co., Ltd.. Invention is credited to Mitsuru Eida, Masahide Matsuura, Hiroshi Tokailin.
United States Patent |
5,909,081 |
Eida , et al. |
June 1, 1999 |
Multi-color light emission apparatus with organic
electroluminescent device
Abstract
This invention provides a multi-color light emission apparatus
wherein a transparent inorganic oxide substrate (4) is disposed
between an organic EL device (1) and a fluorescent layer (3) in
such a manner as to arrange the fluorescent layer (3) with a gap
with the organic EL device (1), and the organic EL device (1) is
sealed by sealing means (5) between the transparent inorganic oxide
substrate (4) and a support substrate (2). The invention provides
also a multi-color light emission apparatus wherein a transparent
insulating inorganic oxide layer (12) having a thickness of 0.01 to
200 .mu.m is interposed between the fluorescent layer (3) and the
organic EL device (1). In this way, light emission life and
angle-of-view characteristics can be improved.
Inventors: |
Eida; Mitsuru (Sodegaura,
JP), Matsuura; Masahide (Sodegaura, JP),
Tokailin; Hiroshi (Sodegaura, JP) |
Assignee: |
Idemitsu Kosan Co., Ltd.
(Tokyo, JP)
|
Family
ID: |
27290760 |
Appl.
No.: |
08/875,756 |
Filed: |
August 6, 1997 |
PCT
Filed: |
February 05, 1996 |
PCT No.: |
PCT/JP96/00233 |
371
Date: |
August 06, 1997 |
102(e)
Date: |
August 06, 1997 |
PCT
Pub. No.: |
WO96/25020 |
PCT
Pub. Date: |
August 15, 1996 |
Foreign Application Priority Data
|
|
|
|
|
Feb 6, 1995 [JP] |
|
|
7-041267 |
Feb 14, 1995 [JP] |
|
|
7-049089 |
Oct 24, 1995 [JP] |
|
|
7-299111 |
|
Current U.S.
Class: |
313/504; 313/506;
345/76; 428/917; 315/169.3; 313/512 |
Current CPC
Class: |
H05B
33/10 (20130101); H01L 51/524 (20130101); H05B
33/12 (20130101); H05B 33/22 (20130101); H01L
51/5253 (20130101); H01L 27/322 (20130101); Y10S
428/917 (20130101); G09G 3/3216 (20130101); H01L
51/5284 (20130101); H01H 2219/053 (20130101) |
Current International
Class: |
H05B
33/12 (20060101); H05B 33/22 (20060101); H01L
51/50 (20060101); H01L 51/52 (20060101); H05B
33/10 (20060101); H01L 27/32 (20060101); G09G
3/32 (20060101); H01L 27/28 (20060101); H05B
033/04 (); H05B 033/14 () |
Field of
Search: |
;313/504,501,506,509,512
;428/917 ;345/76,36,45 ;315/169.3 ;257/40 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Shea; Sandra
Assistant Examiner: Day; Michael
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, P.C.
Claims
What is claimed is:
1. A multi-color light emission apparatus comprising a support
substrate, an organic electroluminescence (EL) device disposed on
the support substrate, and a fluorescent layer disposed to
correspond to a transparent electrode or electrode of the organic
EL device to absorb the light emitted from the organic EL device
and to emit visible fluorescent light, wherein a transparent
inorganic oxide substrate on which the fluorescent layer is placed
is disposed between the organic EL device and the fluorescent layer
in such a manner as to provide a gap between the fluorescent layer
and the organic EL device, and the organic EL device is sealed
using a sealing means between the transparent inorganic oxide
substrate and the support substrate.
2. The multi-color light emission apparatus according to claim 1,
wherein the fluorescent layer is separately disposed on the
transparent inorganic oxide substrate on the same plane.
3. The multi-color light emission apparatus according to claim 1 or
2,
wherein at least a transparent protective layer of the fluorescent
layer and a transparent substrate are farther disposed on the
fluorescent layer.
4. The multi-color light emission apparatus according to claim 1,
wherein the thickness of the transparent inorganic oxide substrate
is in a range of from 1 to 200 .mu.m.
5. The multi-color light emission apparatus according to claim 1,
wherein the transparent inorganic oxide substrate is made of a
transparent glass plate.
6. A multi-color light emission apparatus comprising a transparent
support substrate, fluorescent layers separately disposed on the
transparent support substrate on the same plane, and an organic
electroluminescence (EL) device disposed on or above the
fluorescent layers, the fluorescent layers being disposed to
correspond to a transparent electrode or electrode of the organic
EL device so that each of the fluorescent layers absorbs the light
emitted from the organic EL device and emits different visible
fluorescent light, wherein a transparent and insulating inorganic
oxide layer with a thickness of from 0.01 to 200 .mu.m is
interposed between the fluorescent layer and the organic EL device
wherein at least a transparent protective layer of the fluorescent
layers and a transparent adhesive layer are disposed between the
fluorescent layers and the transparent and insulating inorganic
oxide layer.
7. The multi-color light emission apparatus according to claim 6,
wherein the transparent and insulating inorganic oxide layer is
made of a transparent and insulating glass plate.
8. The multi-color light emission apparatus according to claim 6,
wherein the transparent inorganic oxide layer is made from one or
more compounds selected from a group consisting of silicon oxide,
aluminum oxide, and titanium oxide.
9. The multi-color light emission apparatus according to claim 6,
wherein the transparent and insulating inorganic oxide layer is
produced by forming a film of one or more compounds selected from a
group consisting of silicon oxide, aluminum oxide, and titanium
oxide on at least one of the surface or back face of a transparent
and insulating glass plate.
10. The multi-color light emission apparatus according to claim 6,
wherein the transparent and insulating inorganic layer contains
mainly an inorganic oxide.
Description
FIELD OF THE INVENTION
This invention relates to a multi-color light emission apparatus
and a method for producing thereof. More specifically, this
invention relates to a multi-color light emission apparatus
suitable for use in multi-color or full-color thin-type displays
and a method for producing the multi-color light emission
apparatus.
DESCRIPTION OF THE BACKGROUND ART
An electroluminescence device (hereinafter called "EL device") is
characterized in exhibiting high visibility due to self-emission
and in having excellent impact resistance because of being
completely solid. At present, variable EL devices using an
inorganic or an organic compound as the emitting layer are proposed
and attempts have been made to put them to practical use. One of
the EL devices which has been realized is applied as a multi-color
light emission apparatus.
Such a multi-color light emission apparatus includes an apparatus
produced by combining a color filter of three primary colors (red,
green, and blue) with a white-light emitting inorganic EL device
and an apparatus produced by patterning inorganic EL devices of
three primary colors in order to position the EL devices of three
primary colors separately on the same plane and thereby to emit
light (Semicond. Sci. Technol. 6 (1991) 305-323) However, there is
the problem that the effect of emitting light of each color is
limited to 33% of the white light at most if the white color is
resolved by the color filter of three primary colors. Further, EL
devices which themselves can efficiently emit white light have
still not been attained at present.
On the other hand, a photolithography process is used for
patterning EL devices. However, it is known that the efficiency and
stability of EL devices are greatly reduced in such a wet
process.
It is common knowledge that, among EL devices, organic EL devices
are promising as highly intense and efficient light emitting
devices. In particular, because the light emitting layer is an
organic layer, it is highly probable that various emitting colors
are produced by the molecular design of organic compounds. Such an
organic EL device is expected to be one device which can be used in
practice in a multi-color light emitting apparatus.
However, these organic EL devices have the drawback that chemical
factors such as external steam, oxygen, organic compound gas, and
the like cause deterioration of the EL devices such as reduction in
luminance accompanied by the occurrence of dark spots and the like
and these devices tend to be destroyed from physical (mechanical)
factors such as heat, impact, or the like since the EL devices are
composed of a laminate of low molecular organic compounds.
Therefore, the method for separately disposing each of the organic
EL devices, which emit lights of three primary colors (RGB), on the
same plane can be used in a wet process or a process including heat
treatment such as a photolithography process only with
difficulty.
In order to solve such a problem, disclosed is a color EL display
apparatus (see Japanese Patent Application Laid-open No.
40888/1989). This apparatus is, as shown in FIG. 8, characterized
in that an EL emitting layer 1b sandwiched between a lower
electrode 1c and a light transmitting upper electrode la is
disposed on a substrate 2, the EL light which is output via the
light transmitting electrode la is externally output from a
transmitting substrate 8 via a color filter 9 installed on the
transmitting substrate 8, the color filter 9 facing the
transmitting electrode 1a.
This apparatus has, however, the disadvantage that the luminance of
the light of each color is reduced to one third of the EL light by
the color filter. Also, because the EL device faces the color
filter, the light emission life of the EL device is invariably
reduced by aqueous vapor, oxygen, gas from organic monomers, low
molecular components, and the like generated by the color
filter.
To solve these problems, lately disclosed is a technique in which a
fluorescent layer absorbing light emitted from an organic EL device
and emitting visible fluorescent light is installed in the position
(laminated or in parallel) corresponding to the emitting portion of
the organic EL device (see Japanese Patent Application Laid-open
No. 152897/1991). This technique ensures that the light of a blue
or blue-green color emitted from the organic EL device is converted
into a fluorescent light which is visible light of a longer wave
length. This technique is utilized in a multi-color (three primary
colors) light emission apparatus in which fluorescent layers
capable of converting the blue or blue-green color into a green or
red color are separately disposed on a flat plane (see Japanese
Patent Application Laid-open No. 258860/1993).
The installation of the fluorescent layer has the advantage that
multi-color light emission which is higher in efficiency than in
the case of installing a color filter is expected. Specifically, if
the fluorescent layer especially for converting into a green color
is expected to absorb 80% or more of the blue color light emitted
from the organic EL device, a variety of fluorescent materials
capable of emitting fluorescent light at an efficiency of 80% or
more are known. Assuming both the light absorbing efficiency and
light emitting efficiency of the fluorescent layer to be 80%, it is
estimated that the blue light of the organic EL device can be
converted into visible light with a long wave length at a yield of
64%.
A multi-color light emission apparatus can be realized using an
organic EL device and a fluorescent layer in the above manner.
Japanese Patent Application Laid-open No. 258860/1993 proposes the
following structure for the multi-color light emission
apparatus.
As shown in FIG. 15, fluorescent layers 3R, 3G absorbing the light
emitted from an organic EL device and emitting a green color and
red color respectively are separately disposed on a transparent
substrate 11 on the same plane. A polymer and/or cross-linking
compound of an organic monomer or oligomer and a transparent
insulating rigid plane layer (protective layer) 7 produced by a
sol-gel glass method are laminated on the transparent substrate 11
including the fluorescent layers 3R, 3G by spin casting. A
transparent electrode 1a of the organic EL device is disposed on
the plane layer 7.
Disclosed as other structures are a structure in which the
transparent and insulating flat rigid elements is simply placed on
the surface of the fluorescent layer instead of being laminating on
the fluorescent layer by spin casting and a structure in which the
fluorescent layer is affixed to the back face of the hard element
exhibiting the functions of a flat plane layer instead of affixing
the fluorescent layer to the surface of the substrate. However, it
is reported that the structure shown in FIG. 15 is preferable.
The structure shown in FIG. 15, however, has the problem that the
light emission life of the organic EL device is reduced by aqueous
vapor, oxygen, gas from monomers and the like which are adsorbed to
or included in the organic compound of the flat plane layer in a
slight amount whereby the emission is indispensably non-uniform,
because the transparent electrode of the organic EL device is only
disposed on the same flat layer composed of the polymer and/or
cross-linking compound of an organic monomer or oligomer.
Also, a high temperature treatment at 400.degree. C. or more is
generally required for the production of the flat plane layer in
the sol-gel glass method. This causes the deterioration of the
organic fluorescent layer. If the sol-gel glass flat plane is
produced by heat treatment (up to the maximum temperature of around
250.degree. C.) which never causes the fluorescent member to
deteriorate, there is the problem that the light emission life of
the organic EL device is greatly reduced for the same reason as
above because water or organic compounds remain.
Also, clear explanations about the hard member in the other
structures are not necessarily sufficient.
On the other hand, disclosed is a method in which a glass plate
with a color filter formed by printing is disposed under the back
face of a glass substrate of an inorganic EL device (see Japanese
Patent Application Laid-open No. 119494/1982).
However, a reduction in the emitting efficiency caused by the color
filter is easily predicted in this method. Also, since the organic
EL device is produced independently of the color filter, camber and
distortion of the substrate occur so that the EL device cannot be
manufactured in a stable manner, if, for example, the thickness of
the substrate of the organic EL device is not increased (around 700
.mu.m or more). As a result of the increase in the thickness of the
substrate, the gap between the color filter and the EL device
increases, whereby emitted light of a color other than the desired
emitted colors leaks to remarkably narrow the angle of view when
multi-color light is emitted.
This invention has been achieved in view of this situation and has
an object of providing a multi-color light emission apparatus using
an organic EL device having superior light emission life and
excellent characteristics in the angle of view and a method for
manufacturing the multi-color light emission apparatus in a stable
and efficient manner.
DISCLOSURE OF THE INVENTION
The above object can be attained in a first invention by the
provision of a multi-color light emission apparatus comprising a
support substrate, an organic electroluminescence (EL) device
disposed on the support substrate, and a fluorescent layer disposed
corresponding to a transparent electrode or electrode of the
organic EL device to absorb the light emitted from the organic EL
device and to emit visible fluorescent light, wherein a transparent
inorganic oxide substrate on which a fluorescent layer is placed is
disposed between the organic EL device and the fluorescent layer in
such a manner as to provide a gap between the fluorescent layer and
the organic EL device, and the organic EL device is sealed by a
sealing means between the transparent inorganic oxide substrate and
the support substrate.
In preferred embodiments, the fluorescent layers are separately
disposed on the transparent inorganic oxide substrate on the same
plane;
a protective layer of the fluorescent layers and/or a transparent
substrate are further disposed on the fluorescent layer;
the plate thickness of the transparent inorganic oxide substrate is
in a range of from 1 to 200 .mu.m; and
the transparent inorganic oxide substrate is made of a transparent
glass plate.
The above object can be attained in a second invention by the
provision of a multi-color light emission apparatus comprising a
transparent support substrate, fluorescent layers separately
disposed on the transparent support substrate on the same plane,
and an organic electroluminescence (EL) device disposed on or above
the fluorescent layers, the fluorescent layers being disposed
corresponding to a transparent electrode or electrode of the
organic EL device so that each of the fluorescent layers absorbs
the light emitted from the organic EL device and emits different
types of visible fluorescent light, wherein a transparent and
insulating inorganic oxide layer with a thickness of from 0.01 to
200 .mu.m is interposed between the fluorescent layer and the
organic EL device.
In preferred embodiments, a transparent protective layer of the
fluorescent layers and/or a transparent adhesive layer are disposed
between the fluorescent layer and the transparent and insulating
inorganic oxide layer;
the transparent and insulating inorganic oxide layer is made of a
transparent and insulating glass plate;
the transparent and insulating inorganic oxide layer is made from
one or more compounds selected from a group consisting of silicon
oxide, aluminum oxide, and titanium oxide; and
the transparent and insulating inorganic oxide layer is produced by
forming a film of one or more compounds selected from a group
consisting of silicon oxide, aluminum oxide, and titanium oxide on
at least one of the surface or back face of a transparent and
insulating glass plate.
The above object can be attained in a third invention by the
provision of a method for manufacturing a multi-color light
emission apparatus by separately disposing, on a transparent
support substrate, fluorescent layers absorbing the light emitted
from an organic EL device and emitting different visible
fluorescent light on the same plane and by disposing the organic EL
device on or above the fluorescent layer so that a transparent
electrode or electrode of the organic EL device corresponds to the
fluorescent layer, comprising:
(A) a step of separately disposing the fluorescent layers on the
transparent support substrate on the same plane;
(B) a step of disposing a transparent protective layer of the
fluorescent layers and/or a transparent adhesive layer on the
fluorescent layers and on the transparent support substrate on
which the fluorescent layers are separately disposed;
(C) a step of bonding a transparent and insulating glass plate with
a thickness of from 1 to 200 .mu.m, in which a transparent
electrode is formed or is to be formed, or bonding a member
produced by forming a film made of one or more compounds selected
from a group consisting of silicon oxide, aluminum oxide, and
titanium oxide on at least one of the surface or back face of a
transparent and insulating glass plate, to the transparent
protective layer of the fluorescent layers or to a transparent
adhesive layer; and
(D) a step of laminating an organic compound layer and electrodes
of the organic EL device in order on the glass plate in which the
transparent electrode is formed.
The first to third inventions can provide a multi-color light
emission apparatus using an organic EL device having superior light
emission life and excellent characteristics in the angle of view
and a method for manufacturing the multi-color light emission
apparatus in a stable and efficient manner.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic and typical cross section of an embodiment of
the multi-color light emission apparatus (first invention) of the
present invention.
FIG. 2 is a schematic and typical cross section of the multi-color
light emission apparatus (first invention) of the present invention
showing another embodiment using a protective layer of the
fluorescent layers.
FIG. 3 is a schematic and typical cross section of the multi-color
light emission apparatus (first invention) of the present invention
showing an example using a transparent substrate.
FIG. 4 is a schematic and typical cross section of the multi-color
light emission apparatus (first invention) of the present invention
showing a further embodiment using a fluorescent layer separately
disposed.
FIG. 5 is a schematic and typical cross section of the multi-color
light emission apparatus (first invention) of the present invention
showing an example using a color filter and a black matrix.
FIG. 6 is a schematic and typical cross section of the multi-color
light emission apparatus (first invention) of the present invention
showing an other embodiment using a protective layer of the
fluorescent layers and a transparent substrate.
FIG. 7 is a schematic and typical cross section of a comparative
example, relative to the first invention, wherein a fluorescent
layer is disposed in the same side as an organic EL device on a
transparent glass substrate.
FIG. 8 is a schematic and typical cross section of an example of a
conventional multi-color light emission apparatus.
FIG. 9 is a schematic and typical cross section of an embodiment of
the multi-color light emission apparatus (second invention) of the
present invention.
FIG. 10 is a schematic and typical cross section of the multi-color
light emission apparatus (second invention) of the present
invention showing another embodiment using a transparent adhesive
layer.
FIG. 11 is a schematic and typical cross section of the multi-color
light emission apparatus (second invention) of the present
invention showing a further embodiment using a transparent adhesive
layer and a transparent protective layer of the fluorescent
layers.
FIG. 12 is a schematic and typical cross section of the multi-color
light emission apparatus (second invention) of the present
invention showing a still further embodiment using a transparent
protective layer of the fluorescent layers.
FIG. 13 is a schematic and typical broken view of the multi-color
light emission apparatus (second invention) of the present
invention showing a still further embodiment using a color filter
and a black matrix.
FIG. 14 is a schematic and typical cross section of the multi-color
light emission apparatus (second invention) of the present
invention showing a still further embodiment using a transparent
adhesive layer, a protective layer of the fluorescent layers, and
two transparent and insulating inorganic oxide layers.
FIG. 15 is a schematic and typical cross section of an example of a
conventional multi-color light emission apparatus.
DETAILED DESCRIPTION OF THE INVENTION AND PREFFERED EMBODIMENTS
The multi-color light emitting apparatus of the invention and a
method for manufacturing thereof will now be explained in more
detail.
The organic EL multi-color light emission apparatus of the present
invention must have a structure in which the light (especially a
blue color or blue-green color) emitted from an organic EL device
is efficiently absorbed by a fluorescent layer, without light
reduction and light scattering, and in which a fluorescent light
emitted from the fluorescent layer is externally output without
light reduction and light scattering.
I . Multi-color Light Emission Apparatus (First invention)
From the above points of view, the first invention is specifically
exemplified by the following structures (1)-(3), which are
respectively shown in FIGS. 1-3. Incidentally, a fluorescent layer
may convert the light emitted from an organic EL device into light
of a wave length longer than that of the light emitted from the
organic EL device.
(1) Support substrate 2/organic EL device 1 (electrode 1c/organic
compound layer 1b/transparent electrode 1a)/gap 6/transparent
inorganic oxide substrate 4/fluorescent layer
(2) Support substrate 2/organic EL device 1 (electrode 1c/organic
compound layer 1b/transparent electrode 1a/gap 6/transparent
inorganic oxide substrate 4/fluorescent layer 3/protective layer 7
of the fluorescent layers)
(3) Support substrate 2/organic EL device 1 (electrode 1c/organic
compound layer 1b/transparent electrode 1a/gap 6/transparent
inorganic oxide substrate 4/fluorescent layer 3/transparent
substrate 8)
In the apparatus of the present invention, the organic EL device 1
is sealed by a sealing means 5 formed by bonding the transparent
inorganic oxide substrate 4 to the support substrate 2, for
example, using an adhesive.
Also, in the structures (1) to (3), as shown in FIG. 4, the
fluorescent layers 3 which emit rays of fluorescent light of
different colors are separately disposed on the same plane to
obtain emitted light of the three primary colors (RGB). In this
case, the plate thickness of the transparent inorganic oxide
substrate 4 is preferably in a range of from 1 .mu.m to 200 .mu.m.
Further, as shown in FIG. 5, a color filter 9a may be arranged on
each of the fluorescent layers 3 to control the fluorescent colors
and thereby to promote the color purity. Also, a black matrix 9b
may be disposed between the fluorescent layers or color filters to
prevent light leakage and thereby to promote the visibility of
multi-color emitted light.
Next, the multi-color light emission apparatus of the present
invention will be illustrated in more detail in terms of each
structural element. Materials used for these structural elements
are not limited to the materials described hereinafter which
correspond to the lowest demands of these elements.
1. Organic EL Device
As the organic EL device of the present invention, it is preferable
to use organic EL devices which emit lights ranging from near
ultraviolet light to light of a green color, more preferably a
blue-green color. The following structures are exemplified for the
organic EL device of the present invention to obtain such a light
emission.
These structures comprises fundamentally an emitting layer composed
of an organic compound which is sandwiched between two electrodes
(anode) and (cathode) and other layers may be interposed between
them as required. Typical structures for the organic EL device used
in the present invention are as follows:
(1) Anode/emitting layer/cathode;
(2) Anode/positive hole injection layer/emitting layer/cathode;
(3) Anode/emitting layer/electron injection layer/cathode; and
(4) Anode/positive hole injection layer/emitting layer/electron
injection layer/cathode.
(a) Anode
An anode using, as an electrode material, metals, alloys, electro
conductive compounds, and mixtures of these which have a high work
function (more than 4 ev) are preferably used. Given as examples of
such an electrode material are metals such as Au and electro
conductive materials such as CuI, ITO, SnO.sub.2, and ZnO. A thin
film of each of these electrodes is formed by means of vapor
deposition, sputtering, or the like to produce the anode.
If the light emitted from the emitting layer is taken out of the
anode in this manner, it is desirable that the transmittance by the
anode of the emitted light be more than 10%. In this case, the
anode corresponds to the transparent electrode. Also, the sheet
resistance of the anode is preferably less than several hundreds
.OMEGA./.quadrature.. The thickness of the anode is usually from 10
nm to 1 .mu.m, preferably from 10 nm to 200 nm, although this
depends on the material used.
(b) Emitting layer
Major emitting materials for the organic EL device are organic
compounds. As specific examples of the organic compounds used for
the emitting layer, the following compounds are given, depending on
the desired color.
First, emitted light of ultraviolet to the violet color region can
be prepared using the organic compounds represented by the
following general formula. ##STR1## wherein X represents the
following compound. ##STR2## wherein n denotes 2, 3, 4, or 5, and Y
represents the following compound. ##STR3##
In the above compounds, a phenyl group, phenylene group, and
naphthyl group may be substituted with one or more alkyl groups
having from 1 to 4 carbon atoms, alkoxy groups, hydroxyl groups,
sulphonyl groups, carbonyl groups, amino groups, dimethylamino
groups, and diphenylamino groups. Also, these groups may be
combined to form a saturated five-membered ring or a saturated
six-membered ring. Further, it is preferable that the phenyl group,
phenylene group, and naphthyl group be substituted at a para
position so as to be easily substituted and to form a smooth
deposition film. The compounds represented by the following formula
are given as examples of the compounds substituted at a para
position. Among these compounds, p-quarterphenyl derivatives and
p-quinquephenyl derivatives are preferable. ##STR4##
Next, given as examples of the organic compounds used for producing
emitted light of a blue color to a blue-green color or a green
color are fluorescent bleaching agents such as a benzothiazole
type, benzoimidazole type, and benzoxazole type; metal chelated
oxinoid compounds, and styryl benzene type compounds.
Illustrating specific compounds, for example, the compounds
disclosed in Japanese Patent Application Laid-open No. 194393/1984
are exemplified. Among these, typical examples are fluorescent
bleaching agents including a benzoxazole type such as
2,5-bis(5,7-di-t-pentyl-2-benzoxazolyl)-1,3,4-thiadiazole,
4,4'-bis(5,7-di-t-pentyl-2-benzoxazolyl)stilbene,
4,4'-bis(5,7-di-(2-methyl-2-butyl)-2-benzoxazolyl)stilbene,
2,5-bis(5,7-di-t-pentyl-2-benzoxazolyl)thiophene,
2,5-bis(5-.alpha.,.alpha.-dimethylbenzyl-2-benzoxazolyl)thiophene,
2,5-bis(5-7-di(2-methyl-2-butyl)-2-benzoxazolyl)-3,4-diophenylthiophene,
2,5-bis(5-methyl-2-benzoxazolyl) thiophene, 4,
4'-bis(2-benzoxazolyl)biphenyl,
5-methyl-2-[2-[4-(5-methyl-2-benzoxazolyl)phenyl]vinyl]benzoxazole,
2-[2-(4-chlorophenyl)vinyl]naphtho[1,2-d]oxazole, and the like;
benzothiazole type such as
2-2'-(p-phenylenedivinylene)-bisbenzothiazole and the like; and
benzoimidazole type such as
2-[2-[4-(2-benzoimidazolyl)phenyl]vinyl]benzoimidazole,
2-[2-(4-carboxyphenyl)vinyl]benzoimidazole, and the like. In
addition, other useful compounds are enumerated in Chemistry of
Synthetic Dyes, 628-637, P640, (1971).
As the above-mentioned chelated oxinoid compounds, the compounds
disclosed in Japanese Patent Application Laid-open No. 295695/1988
can be used. Among these, typical examples are 8-hydroxyquinoline
type metal complexes such as tris(8-quinolinol) aluminum,
bis(8-quinolinol) magnesium, bis(benzo[f]-8-quinolinol) zinc,
bis(2-methyl-8-quinolinolate) aluminum oxide, tris(8-quinolinol)
indium, tris (5-methyl-8-quinolinol) aluminum, 8-quinolinol
lithium, tris (5-chloro-8-quinolinol) gallium,
bis(5-chloro-8-quinolinol) calcium,
poly[zinc(II)-bis(8-hydroxy-5-quinolinonyl)methane], and the like
and dilithium epinetridione.
As the above-mentioned styryl benzene type compounds, the compounds
disclosed in the specifications of EPCs No. 0319881 and No. 0373582
can be also used. Typical examples of these styryl benzene type
compounds are 1,4-bis(2-methylstyryl)benzene,
1,4-bis(3-methylstyryl)benzene, 1,4-bis(4-methylstyryl)benzene,
distyrylbenzene, 1,4-bis(3-ethylstyryl)benzene,
1,4-bis(2-methylstyryl)-2-methylbenzene,
1,4-bis(2-methylstyryl)-2-ethylbenzene, and the like.
Further, distyryl pyrazine derivatives disclosed in Japanese Patent
Application Laid-open No. 252793/1990 can be used as the material
for the emitting layer. Typical examples of these derivatives are
2,5-bis(4-methylstyryl)pyrazine, 2,5-bis(4-ethylstyryl)pyrazine,
2,5-bis[2-(1-naphthyl)vinyl]pyrazine,
2,5-bis(4-methoxystyryl)pyrazine,
2,5-bis[2-(4-biphenyl)vinyl]pyrazine,
2,5-bis[2-(1-pyrenyl)vinyl]pyrazine, and the like.
In addition, the polyphenyl type compounds disclosed in the
specification of EPC No. 0387715 can be used as the material for
the emitting layer.
Other than the above-mentioned fluorescent bleaching agents, metal
chelated oxinoid and styryl benzene, the following compounds can be
used as the material for the emitting layer:
12-phthaloperinone (J. Appl. Phys., Vol 27, L713, (1988)),
1,4-diphenyl-1,3-butadiene, 1,1,4,4-tetraphenyl-1,3 butadiene
(Appl. Phys. Lett., Vol 56, L799, (1990)), naphthalimide
derivatives (Japanese Patent Application Laid-open No.
305886/1990), perillene derivatives (Japanese Patent Application
laid-open No. 189890/1990), oxadiazole derivatives (Japanese Patent
Application Laid-open No. 216791/1990 or oxadiazole derivatives
disclosed by Hamada et al. at the conference of Appl. Phys),
aldazine derivatives (Japanese Patent Application Laid-open No.
220393/1990), pyraziline derivatives (Japanese Patent Application
Laid open No. 220394/1990), cyclopentadiene derivatives (Japanese
Patent Application Laid-open No. 289675/1990), pyrrolopyrrole
derivatives (Japanese Patent Application Laid-open No.
296891/1990), styrylamine derivatives (Appl. Phys. Lett., Vol 56,
L799, (1990)), coumarine type compounds (Japanese Patent
Application Laid-open No. 191694/1990), and macromolecular
compounds described in the International Disclosure Official
Gazette WO90/13148 or Appl. Phys. Lett., Vol 58, 18, P1982
(1991).
In the present invention, as the materials used for the emitting
layer, aromatic dimethylidine type compounds (compounds disclosed
in the specification of EPC No. 0388768 or Japanese Patent
Application Laid-open NO. 231970/1991) are preferably used.
Specific Examples of such compounds are 1,4-phenylenedimethylidyne,
4,4-phenylenedimethylidyne, 2,5-xylenedimethylidyne,
2,6-naphthylenedimethylidyne, 1,4-biphenylenedimethylidyne,
1,4-p-terephenylenedimethylidyne, 9,10-anthracenediyldimethylidyne,
4,4'-bis(2,2-di-t-butylphenylvinyl)biphenyl (hereinafter
abbreviated as (DTBPVBi)), 4,4'-bis(2,2-diphenylvinyl)biphenyl
(hereinafter abbreviated as (DPVBi), and derivatives of these.
Also, the compounds represented by the general formula (R.sub.s
--Q).sub.2 --AL--O--L, which are described in Japanese Patent
Application Laid-open No. 258862/1993 can be used, wherein L
represents a hydrocarbon having 6-24 carbon atoms and including a
phenyl group, O-L represents a phenolate ligand, Q represents a
substituted 8-quinolinolate ligand, Rs represents an
8-quinolinolate ring substitutional group selected to
stereo-chemically prevent three or more substituted 8-quinolinolate
ligands from binding with an aluminum atom.
Given as specific examples of such compounds are
bis(2-methyl-8-quinolinolate)(para-phenylphenolate) aluminum (III)
(hereinafter abbreviated as (PC-7)) and
bis(2-methyl-8-quinolinolate)(1-naphtholate) aluminum (III)
(hereinafter abbreviated as (PC-17)).
In addition, Japanese Patent Application Laid-open No. 9953/1994
discloses a method for producing mixed emitted light of a blue
color and a green color by doping in an efficient manner. When
using this method for forming the emitting layer of the present
invention, the above-mentioned emitting material is used as a host.
As a dopant, a strongly fluorescent coloring material of a blue
color to a green color, for example, a coumarin type or fluorescent
coloring material similar to those used in the above method can be
given. Specifically, as the host, fluorescent materials mainly
composed of distyryl arylene, preferably, for example, DPVBi can be
given. As the dopant, diphenylaminostyryl arylene, preferably, for
example, 1,4-bis{4-N,N'-diphenylamino}styryl}benzene (DPAVB) can be
given.
As the methods for forming an emitting layer using the above
materials, known methods, for example, a vapor deposition method, a
spin-coating method, a LB method, or the like can be applied. A
preferred emitting layer is especially a molecularlysedimentary
film. The molecularly sedimentary film is a film formed by
deposition of a subject compound in a vapor phase or a film formed
by solidifying a subject compound in a solution or in a liquid
phase. The molecularly sedimentary film is generally distinguished
from a thin film (molecularly cumulative film) formed in the LB
method by differences in a coagulating structure and a high-order
structure, or by a functional difference caused by those
structures.
Also, the emitting layer can be formed in a similar manner by a
method disclosed in Japanese Patent Application Laid-open No.
51781/1982 in which a binding agent such as a resin and a subject
compound are dissolved in a solvent to make a solution and then a
thin film is formed from the solution using a spin-coating method
or the like.
The thickness of the emitting layer is preferably in a range from 5
nm to 5 .mu.m, though there are no limitations to the thickness of
the emitting layer produced in such a manner and the thickness of
the emitting layer is optionally selected.
The emitting layer of the organic EL device has also the following
functions.
(1) Injection functions which allow positive holes to be injected
from an anode or a positive hole injecting layer in the presence of
an electric field and allow electrons to be injected from a cathode
or an electron injecting layer.
(2) Transferring functions which allow the injected charges
(electrons and positive holes) to be transferred by electric field
force.
(3) Emitting functions which allows electrons and positive holes to
be combined to emit light.
Incidentally, there may be a difference in ease between the
injecting of electrons and the injecting of positive holes. Also,
there maybe adifference between the transferability of positive
holes and that of electrons in terms of mobility. However, it is
desirable to transfer either positive holes or electrons.
(c) Positive hole injecting layer
Any material optionally selected from photo-conductive materials
conventionally used as a material for transferring a charge of
positive holes and from known materials used for a positive hole
injecting layer of an organic EL device can be used as the material
for the positive hole injecting layer provided as required. The
material for the positive hole injecting layer which has a function
either as a positive hole injecting layer or as a barrier for an
electron may be either an organic or inorganic compound.
Given as examples of these conventional materials are triazole
derivatives (see the specification of U.S. Pat. No. 3,112,197,
etc.), oxadiazole derivatives (see the specification of U.S. Pat.
No. 3,189,447, etc.), imidazole derivatives (Japanese Patent
Publication No. 16096/1962, etc.), polyarylalkane derivatives (see
the specifications of U.S. Pat. No. 3,615,402, U.S. Pat. No.
3,820,989, U.S. Pat. No. 3,542,544, Japanese Patent Publications
No. 555/1970 and No. 10983/1976, and Japanese patent Applications
laid-open No. 93224/1976, No. 17105/1980, No. 4148/1981, No.
108667/1980, No. 156953/1980, and No. 36656/1981, etc.), pyrazoline
derivatives and pyrazolone derivatives (see the specifications of
U.S. Pat. No. 3,180,729, U.S. Pat. No. 4,278,746, and Japanese
Patent Applications Laid-open No. 88064/1980, No. 88065/1980, No.
105537/1974, No. 51086/1980, No. 80051/1981, No. 88141/1981, No.
45545/1982, No. 112637/1979, and No. 74546/1980, etc.),
phenylenediamine derivatives (see the specifications of U.S. Pat.
No. 3,615,404, Japanese Patent Publications No. 10105/1976, No.
3712/1971, and No. 25336/1972, Japanese Patent Applications
Laid-open No. 53435/1979, No. 110536/1979, and No. 119925/1979,
etc.), arylamine derivatives (see the specifications of U.S. Pat.
No. 3,567,450, U.S. Pat. No. 3,240,597, U.S. Pat. No. 3,658,520,
U.S. Pat. No. 4,232,103, U.S. Pat. No. 4,175,961, U.S. Pat. No.
4,012,376, Japanese Patent Publications No. 35702/1974 and No.
27577/1964, Japanese Patent Applications Laid-open No. 144250/1980,
No. 119132/1981, and No. 22437/1981, and DRP No. 1,110,518, etc.),
amino substituted chalcone derivatives (see the specification of
U.S. Pat. No. 3,526,501, etc.), oxazole derivatives (see the
specification of U.S. Pat. No. 3,257,203, etc.), styrylanthracene
derivatives (see the specification of Japanese Patent Application
Laid-open No. 46234/1981, etc.), fluorenone derivatives (see the
specification of Japanese Patent Application Laid-open No.
110837/1979 and etc.), hydrazone derivatives (see the
specifications of U.S. Pat. No. 3,717,462, Japanese Patent
Applications Laid-open No. 59143/1979, No. 52063/1980, No.
52064/1980, No. 46760/1980, No. 85495/1980, No. 11350/1982, No.
148749/1982, and No. 311591/1990, etc.), stilbene derivatives (see
the specifications of Japanese Patent Applications Laid-open No.
210363/1986, No. 228451/1986, No. 14642/1986, No. 72255/1986, No.
47646/1987, No. 36674/1987, No. 10652/1987, No. 30255/1987, No.
93445/1985, No. 94462/1985, No. 174749/1985, and No. 175052/1985,
etc.), silazane derivatives (see the specification of U.S. Pat. No.
4,950,950, etc.), polysilane type (see the specification of
Japanese Patent Application Laid-open No. 204996/1990, etc.),
aniline type copolymers (see the specification of Japanese Patent
Application Laid-open No. 282263/1990, etc.), and electro
conductive macromolecular oligomers (especially a thiophene
oligomer) disclosed in Japanese Patent Application Laid-open No.
211399/1989.
As the materials used for the positive hole injecting layer, the
above compounds can be used. Among these, polphyrin compounds
(disclosed in Japanese Patent Application Laid-open No.
2956965/1988) and aromatic tertiary amines and styrylamine
compounds (see the specifications U.S. Pat. No. 4,127,412, Japanese
Patent Applications Laid-open No. 27033/1978, No. 58445/1979, No.
149634/1979, No. 64299/1979, No. 79450/1980, No. 144250/1980, No.
119132/1981, No. 295558/1986, No. 98353/1986, and No. 295695/1988,
etc.) are preferable. It is especially preferable to use the
aromatic tertiary amines.
Typical examples of the above porphyrin compounds are porphin,
1,10,15,20-tetraphenyl-21H, 23H-porphin copper (II),
1,10,15,20-tetraphenyl-21H, 23H-porphin zinc (II),
5,10,15,20-tetrakis(pentafluorophenyl)-21H, 23H-porphin, silicon
phthalocyanine oxide, aluminum phthalocyanine chloride,
phthalocyanine (non-metal), dilithium phthalocyanine, copper
tetramethylphthalocyanine, copper phthalocyanine, chromium
phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium
phthalocyanine oxide, magnesium phthalocyanine, copper
octamethylphthalocyanine, and the like.
Typical examples of the above aromatic tertiary amine and
styrylamine compounds are N,N,N',N'-tetraphenyl-4,4'-diaminophenyl,
N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine
(hereinafter abbreviated as "TPD"), 2,2-bis
(4-di-p-tolylaminophenyl)propane,
1,1-bis(4-di-p-tolylaminophenyl)cyclohexane,
N,N,N',N'-tetra-p-tolyl-4,4'-diaminophenyl,
1,1-bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane,
bis(4-dimethylamino-2-methylphenyl)phenylmethane,
bis(4-di-p-tolylaminophenyl)phenylmethane,
N,N'-diphenyl-N,N'-di(4-methoxyphenyl)-4,4'-diaminobiphenyl,
N,N,N',N'-tetraphenyl-4,4'-diaminophenyl ether,
4,4-bis(diphenylamino)quadriphenyl, N,N,N-tri(p-tolyl)amine,
4-(di-p-tolylamino)-4'-[4(di-p-tolylamino)styryl]stilbene,
4-N,N-diphenylamino-(2-diphenylvinyl)benzene,
3-methoxy-4'-N,N-diphenylaminostylbenzene, N-phenylcarbazole,
compounds having two condensed aromatic rings in a molecule, for
example, 4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl
(hereinafter abbreviated as (NPD)) disclosed in U.S. Pat. No.
5,061,569, and compounds in which three triphenylamine units are
combined in a star-burst shape, for example,
4,4',4"-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine
(hereinafter abbreviated as (MTDATA)) disclosed in Japanese Patent
Application Laid-open No. 308688/1992, and the like.
Also, other than the above-mentioned aromatic dimethylidine
compounds shown as the material for the emitting layer, inorganic
compounds such as p type Si and p type SiC can be utilized as the
material used for the positive hole injecting layer.
The positive hole injecting layer can be produced by forming a thin
film of the above-mentioned compound using a conventional method
such as a vacuum deposition method, spin-coating method, casting
method, LB method, or the like. There are no restrictions as to the
thickness of the positive hole injecting layer. However, the
thickness of the positive hole injecting layer is generally from 5
nm to 5 .mu.m. This positive hole injecting layer may be structured
of one layer made from one or more of the above materials or may be
a layer in which other positive hole injecting layers made from
compounds differing from the compound of that layer are laminated
on that layer.
(d) Electron injecting layer
The electron injecting layer provided as required may have the
function of transferring, to the emitting layer, the electrons
injected from the cathode. Optionalcompounds selected from
conventionally known compounds may be used.
Typical examples of these compounds include nitro-substituted
fluorene derivatives; anthraquinodimethane derivatives disclosed in
Japanese Patent Applications Laid-open No. 149259/1982, No.
55450/1983, and No. 104061/1988; diphenylquinone derivatives,
thiopyrane dioxide derivatives, heterocyclic tetracarboxylic acid
anhydrides such as naphthaleneperillene and the like, and
carbodiimides which are all disclosed in Polymer Preprints, Japan
Vol. 37. No. 3 (1988) p. 681 and the like; fluorenylidenemethane
derivatives disclosed in Japanese Journal of Applied Physics, 27,
L269 (1988), Japanese Patent Applications Laid-open No.
696657/1985, No. 143764/1986, and No. 148159/1986;
anthraquinonedimethane and anthrone derivatives disclosed in
Japanese Patent Applications Laid-open No. 225151/1986 and No.
233750/1986; oxadiazole derivatives disclosed by the
above-described Hamada et al. at the conference of Appl. Phys; and
a series of an electron transfer compounds disclosed in Japanese
Patent Application Laid-open No. 194393/1984. Incidentally, though
the above electron transfer compounds are disclosed as the
materials used for the emitting layer in Japanese Patent
Application Laid-open No. 194393/1984, it is confirmed as a result
of the studies of the present inventors that these compounds can be
used as the materials for the electron injecting layer.
Also, thiazole derivatives produced by replacing an oxygen atom of
the above oxadiazole ring with a sulfur atom and quinoxaline
derivatives having a quinoxaline ring known as an electron
attracting group are given as examples of the materials for the
electron injecting layer. Further, included as examples of the
materials for the electron injecting layer are metal complexes of
8-quinolinole, specifically, tris(8-quinolinole) aluminum
(hereinafter abbreviated as "Alq"), tris(5,7-dibromo-8-quinolinole)
aluminum, tris(2-methyl-8-quinolinole) aluminum,
tris(5-methyl-8-quinolinole) aluminum, bis(8-quinolinole) zinc
(hereinafter abbreviated as "Znq"), and metal complexes produced by
replacing the primary metals of these metal complexes with In, Mg,
Cu, Ca, Sn, Ga, or Pb.
Other than the above, metal-free or metal phthalocyanine compounds
of 8-quinolinole derivatives or compounds produced by replacing the
terminal group of these compounds with an alkyl group, sulphonic
acid group, or the like. Also, the distyryl pyrazine derivatives
can be used as the materials for the electron injecting layer.
Similar to the positive hole injecting layer, inorganic
semiconductors such as n-type-Si, n-type-SiC, or the like may be
used.
The electron injecting layer can be produced by forming a thin film
of the above-mentioned compound using a conventional method such as
a vacuum deposition method, spin-coating method, casting method, LB
method, or the like. There are no restrictions as to the thickness
of the electron injecting layer. However, the thickness of the
electron injecting layer is generally from 5 nm to 5 .mu.m. This
electron injecting layer may be structured of one layer made from
one or more of the above materials or may be a layer in which other
electron injecting layers made from compounds differing from the
compound of that layer are laminated on that layer.
(e) Cathode
As examples of the cathode, those using, as an electrode material,
metals (these are called "electron injecting metal"), alloys,
electro conductive compounds, and mixtures of these which have a
low work function (less than 4 eV) are used. Given as examples of
such an electrode material are metals such as sodium,
sodium/potassium alloy, magnesium, lithium, magnesium/copper
mixtures, magnesium/silver mixtures, magnesium/aluminum mixtures,
magnesium/indium mixtures, aluminum/aluminum oxide (Al.sub.2
O.sub.3), indium, lithium/aluminum mixtures, and rare earth metals,
and the like. Among these, preferred examples are mixtures of the
electron injecting metal and a secondary metal which has a high
work function and is stable in consideration of electron injecting
capability and durability to oxidation as an electrode.
Specifically, magnesium/silver mixtures, magnesium/aluminum
mixtures, magnesium/indium mixtures, aluminum/aluminum oxide
(Al.sub.2 O.sub.3), and lithium/aluminum mixtures are given as the
preferred examples.
A thin film of each of these electrode materials is formed by means
of vapor deposition, sputtering, or the like to produce the
cathode.
If the light emitting from the emitting layer is taken out of the
cathode in this manner, it is desirable that the transmittance by
the cathode of the emitted light be more than 10%. In this case,
the cathode corresponds to the transparent electrode.
Here, the sheet resistance of the cathode is preferably less than
several hundreds .OMEGA./.quadrature.. The thickness of the cathode
is usually from 10 nm to 1 .mu.m, preferably from 50 nm to 200
nm.
In the multi-color light emission apparatus using an organic EL
device as a emitting member, for example, one electrode pattern
line perpendicular to another pattern line is usually formed. When
forming the electrode on a thin film of an organic compound layer
such as an emitting layer or the like using a photolithography
method including wet etching, an organic compound layer is caused
to greatly deteriorate so that the photography method cannot be
used in a stable manner. Therefore, the electrode pattern is formed
through a mask having a desired shape when the electrode (anode or
cathode) materials are treated by vapor deposition or sputtering.
When the electrode is not formed on a thin film of the organic
compound layer for example on the glass plate, the pattern of the
electrode pattern may be formed by photolithography.
(f) Manufacture of organic EL device (example)
Using the above exemplified materials and methods, anode (for
example, transparent electrode), an emitting layer, positive hole
injecting layer as required, and electron injecting layer as
required are formed and further a cathode (for example, electrode)
is formed in that order to manufacture an organic EL device. Also,
an organic EL device can be manufactured in the reverse order.
A manufacturing example of an organic EL device having a structure
in which an anode, a positive hole injecting layer, a emitting
layer, an electron injecting layer, and a cathode are provided in
that order on a support substrate is illustrated below.
First, a thin film of a thickness of less than 1 .mu.m, preferably
from 10 to 200 nm is formed of an anode material by vapor
deposition, sputtering, or the like to form an anode. Next, a
positive hole injecting layer is formed on the anode. Formation of
the positive hole injecting layer can be carried out, as mentioned
above, by means of vacuum deposition, spin-coating, casting, LB, or
the like. Among these means, vacuum deposition is preferable to
form a homogeneous film with ease and to prevent occurrence of pin
holes. When forming the positive hole injecting layer by means of
vacuum deposition, the depositing conditions differ depending on
the sort of compound (material for the positive hole injecting
layer) to be used, the crystalline structure and the recombination
structure of the object positive hole injecting layer, and the
like. However, it is generally preferable to appropriately select
the depositing conditions from a depositing source temperature
ranging from 50 to 450.degree. C., a vacuum ranging from 10.sup.-7
to 10.sup.-3 torr, a depositing speed ranging from 0.01 to 50
nm/sec, a substrate temperature ranging from -50 to 300.degree. C.,
and a film thickness ranging from 5 nm to 5 .mu.m.
Next, an emitting layer is formed on the positive hole injecting
layer using a desired organic emitting material. Formation of the
emitting layer can be carried out by providing a thin film of the
organic emitting material by means of vacuum deposition,
sputtering, spin-coating, and casting. Among these means, vacuum
deposition is preferable to form a homogeneous film with ease and
to prevent occurrence of pin holes. When forming the emitting layer
by means of vacuum deposition, the depositing conditions differ
depending on the sort of compound to be used. Generally, the
depositing conditions can be selected from almost the same
condition ranges as in the formation of the positive hole injecting
layer.
Next, an electron injecting layer is formed on the emitting layer.
It is preferable to form the electron injecting layer by vacuum
deposition to produce a homogeneous film in the same way as in the
formation of the positive hole injecting layer or the emitting
layer. The depositing conditions can be selected from almost the
same condition ranges as in the formation of the positive hole
injecting layer or the emitting layer.
Finally, a cathode is laminated on the electron injecting layer to
produce an organic EL element.
The cathode is formed of a metal so that vapor deposition or
sputtering can be used. However, vacuum deposition is preferably
used to protect the backing organic material from damage in forming
a film.
When the organic EL device are produced in the above-mentioned
processes, it is preferable that the steps from the step of forming
the anode to the step of forming the cathode are thoroughly
processed in one evacuating operation.
Incidentally, in the case where a d.c. voltage is applied to the
organic EL device, when applying 5-40 volts, allowing the anode and
the cathode to be provided with the positive (+) polarity and the
negative (-) polarity respectively, luminance can be detected. When
both the anode and the cathode are inversely polarized, current
never flows and luminance is not detected. Further, if an a.c.
voltage is applied, luminance can be detected only at the time when
the anode and the cathode are respectively polarized to the (+)
polarity and the (-) polarity. The wave form of the a.c. current to
be applied is optional.
2. Support Substrate
Materials which are not composed of an organic compound are
preferable as the materials for the support substrate used in the
present invention. Transparency is not required for the materials
of the support substrate. Materials which are shielded from light
are rather preferable to output light from the fluorescent layer.
It is desirable that at least the surface of the support substrate
facing the organic EL device be composed of an insulating material.
There are no limitations to the thickness of the support substrate
to the extent that it can reinforce a thin transparent glass plate
to be laminated subsequently without camber and distortion.
Typically, for example, a ceramic plate, metal plates which are
processed by insulating treatment using inorganic oxides such as
silica, alumina, or the like can be used as the materials for the
support substrate. In the case of using transparent materials such
as glass plates (soda lime glass, heat resistance glass, and the
like), quartz glass plates, or the like, the surface opposite to
the organic EL device may be provided with a light-shielding film,
reflecting plate with a black film, or the like.
3. Fluorescent Layer
The fluorescent layer used in the present invention is composed of,
for example, a fluorescent coloring material and a resin or of an
independent fluorescent coloring material. The fluorescent layer
composed of the fluorescent coloring material and the resin are,
for example, a solid type produced by dissolving or dispersing the
fluorescent coloring material in the binder resin.
Specific examples of types of coloring material will be explained.
First given as examples of the coloring material converting
ultraviolet or violet emission of the organic EL device to blue
emission are stilbene type coloring materials such as
1,4-bis(2-methyl styryl) benzene (hereinafter abbreviated as
(Bis-MSB)) and trans-4,4'-diphenyl stilbene (hereinafter
abbreviated as (DPS)) and coumarin type coloring materials such as
7-hydroxy-4-methyl coumarin (hereinafter abbreviated as (coumarin
4)).
Given as examples of the coloring material converting blue or
blue-green emission of the organic EL device to green emission are
a coumarin type coloring material such as 2,3,5,6-1H,
4H-tetrahydro-8-trifluoromethylquinolizino(9,9a,1-gh)coumarin
(hereinafter abbreviated as (coumarin 153)),
3-(2'-benzothiazolyl)-7-diethylaminocoumarin (hereinafter
abbreviated as (coumarin 6)), and
3-(2'-benzimidazolyl)-7-N,N'-diethylaminocoumarin (hereinafter
abbreviated as (coumarin 7)), other coumarin coloring material type
dyes such as basic yellow 51, and naphthalimide type coloring
materials such as solvent yellow 11 and solvent yellow 116.
Given as examples of the coloring material converting blue-green
emission of the organic EL device to orange-red emission are
cyanine type coloring materials such as
4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4-H-pyran
(hereinafter abbreviated as (DCM)), pyridine type coloring
materials such as
1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridinium-perchlorat
e (hereinafter abbreviated as (pyridine 1)), rhodamine type
coloring materials such as rhodamine B and rhodamine 6G, and
oxazine type coloring materials.
Further, various dyes (direct dye, acidic dye, basic dye, disperse
dye) can be used provided that they exhibit fluorescence. Also,
pigmental materials in which the above fluorescent coloring
material is kneaded in advance in a pigmental resin such as
polymethacrylate ester, polyvinyl chloride, vinyl chloride-vinyl
acetate copolymer, alkyd resin, aromatic sulphonamide resin, urea
resin, melamine resin, benzoguanamine resin, or the like may be
used.
In addition, these types of fluorescent coloring materials and
pigments may be, as required, used either independently or in
combination. The conversion rate of the fluorescent coloring
material to red color is low. By mixing the above pigments, the
rate of conversion from light emission to fluorescent emission can
be increased.
On the other hand, as the binder resin, transparent materials
(transmittance of visible rays: more than 50%) are preferable.
Given as examples of such transparent materials are transparent
resins (polymer) such as polymethyl methacrylate, polyacrylate,
polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone,
hydroxyethyl cellulose, and carboxymethyl cellulose.
Incidentally, photosensitive resins which can be used in
photolithography are also selected to separately dispose the
fluorescent layers on the same plane. For example, photocurable
resists having a reactive vinyl group such as an acrylate type,
methacrylate type, vinyl polycinnamate type, and cyclic rubber type
are given as examples of the photosensitive resins. When using a
printing method, printing inks (medium) using a transparent resin
are selected. Given as examples of these transparent resins are a
polyvinyl chloride resin, melamine resin, phenol resin, alkyd
resin, epoxy resin, polyurethane resin, polyester resin, maleic
acid resin, monomers, oligomers, and polymers of a polyamide resin,
polymethylmethacrylate, polyacrylate, polycarbonate, polyvinyl
alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, and
carboxymethyl cellulose.
The fluorescent layers are commonly manufactured by the following
processes. The fluorescent layers mainly composed of fluorescent
coloring materials are manufactured by forming a film using a
vacuum deposition method or a sputtering method through a mask on
which a desired pattern is formed for the fluorescent layers. On
the other hand, the fluorescent layers composed of fluorescent
coloring materials and a resin are manufactured by mixing
fluorescent coloring materials, a resin, and a resist, dispersing
or solubilizing to allow the mixture to be liquefied, forming a
film using a spin-coating method, roll-coating method, or casting
method, and patterning with a desired pattern for the fluorescent
layers using a photolithographic method or a screen printing
method.
There are no limitations to the thickness of the fluorescent layers
to the extent that the emission of the organic EL elements is
sufficiently absorbed and the function of emitting fluorescent
light is not impaired. The thickness of the fluorescent layers is
in a range of from 10 nm to 1 mm approximately.
For the fluorescent layer composed, especially, of fluorescent
coloring materials and a binder resin, the concentration of the
fluorescent coloring material may be in such a range as that the
emission of the organic EL device can be absorbed efficiently
without concentration quenching of fluorescence. The concentration
of the fluorescent coloring material is in a range of from 1 to
10.sup.+4 mol/kg approximately to the binder resin to be used,
though this depends on the type of the fluorescent coloring
material.
In addition, because the fluorescence conversion efficiency,
especially, to a red color is low, fluorescent layers of a green
color and a red color may be laminated to improve the
efficiency.
4. Transparent Inorganic Oxide Substrate
As examples of the transparent inorganic oxide substrate used in
the present invention, a substrate composed of a transparent and
electrically insulating inorganic oxide layer as shown in the
second invention is given. However, the substrate is not
necessarily formed of an electrically insulating material.
Such an inorganic oxide substrate has a high efficiency in
shielding, especially, aqueous vapor, oxygen, organic compound gas,
and the like.
It is desirable that the plate thickness be as small as possible to
improve the characteristics in the angle of view, when the
fluorescent layers which absorb the light emission from the organic
EL device and emit different fluorescent emission are separately
disposed on the same plane to emit multi-color light such as the
three primary colors (RGB).
Usually, inorganic oxide substrates with a thickness of from 700
.mu.m to 1.1 mm are often used for a liquid crystal. However, in
the present case, an inorganic oxide substrate with a thickness of
from 1 .mu.m to 700 .mu.m, and preferably from 1 .mu.m to 200 .mu.m
is used.
If the thickness of the inorganic oxide substrate is not greater
than 1 .mu.m, it is difficult to handle the inorganic oxide
substrate which tends to be broken. Also, when such inorganic oxide
substrate is applied to the support substrate on which the organic
EL devices are laminated, using a sealing means, the inorganic
oxide substrate is bent, showing remarkable camber or distortion.
On the other hand, if the thickness exceeds 200 .mu.m, there is the
case where the light emitted from the organic EL device leaks from
gaps between the inorganic oxide substrate and the fluorescent
layer, which causes a narrow angle of view for multi-color light
emission, thereby reducing practicability, though this depends on
the fineness of the fluorescent layer.
5. Sealing Means
There are no limitations as to the sealing means used in the
present invention. Materials, for example, composed of an ordinary
adhesive may be used as the sealing means.
Specifically, given as examples of the adhesive are photocurable or
heatcurable adhesives having a reactive vinyl group of an acrylate
type oligomer and methacrylate type oligomer; and moisture-curable
adhesives such as 2-cyanoacrylate and the like. In addition, heat
and chemical curable type adhesives (two-liquid mixing type) can be
used. Also, hotmelt type polyamide, polyester, and polyolefin are
given as examples of the adhesive. Adhesives capable of adhering
and curing at from room temperature to 80.degree. C. are preferable
because there is the case where the organic EL device deteriorates
from heat treatment.
Application of the adhesive to a sealing portion may be carried out
using a dispenser or by printing such as screen printing.
There is no problem in curing after the application in the case of
using visible light. However, there is the case where the organic
EL device deteriorates when UV light is used and hence a method in
which the organic EL device is never irradiated with UV light such
as by masking or the like is effective.
6. Gap
In the present invention, the gap provided between the transparent
inorganic oxide substrate and the organic EL device is used to
absorb impact or stress on the organic EL device. If a material
used for a sealing means is directly applied to the organic EL
device, the organic EL device tends to be broken by the stress
produced when the material is cured.
It is desirable that inert gas such as nitrogen, argon, or the
like, or an inactive liquid such as hydrocarbon fluoride or the
like be sealed into the gap, because the organic EL device are
liable to be oxidized by air if only air is present in the gap.
If the width of the gap is large in the case of using very fine
multi-color light emission, light leakage increases and hence the
angle of view is greatly reduced. Therefore, the width of the gap
should be preferably small, specifically from several .mu.m to 200
.mu.m in general, though this depends on the fineness of the
multi-color light emission.
7. Protective Layer of the Fluorescent Layers (transparent flat
film)
A protective layer of the fluorescent layers (transparent flat
film) used as required in the present invention is used so that the
fluorescent layer and color filter (including a black matrix)
located at the outside of the multi-color light emission apparatus
are protected from physical damage and deterioration from
externally environmental factors such as water, oxygen, light, and
the like. The protective layer is preferably composed of a
transparent material with a visible light transmittance of 50% or
more.
Specifically, as examples of the material for the protective layer,
compounds having a reactive vinyl group of an acrylate type or
methacrylate type such as a photocurable resin and/or heat-curable
resin can be given.
Also, given as examples of the material for the protective layer
are transparent materials such as a melamine resin, phenol resin,
alkyd resin, epoxy resin, polyurethane resin, polyester resin,
maleic acid resin, monomer, polymer, or oligomer of a polyamide
resin, polymethyl methacrylate, polyacrylate, polycarbonate,
polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose,
and the like.
A UV ray absorber may be added to the protective layer to improve
the light resistance of the fluorescent layer.
The protective layer is prepared by forming a film of the above
material by spin-coating, roll coating, casting, or the like when
the material is liquid. If the material is a photocurable resin,
the film is irradiated with UV rays and is heat-cured as required,
whereas if the material is a heat-curable resin, the film is
heat-cured as is after the film is formed. On the other hand, when
the material is shaped as a film, the material may be applied to
the fluorescent layer using an adhesive.
There are no limitations as to the thickness of the protective
layer since it has no influence on the angle of view. However, when
the thickness is too great, it has some influence on the light
transmittance, so that the thickness is preferably in a range from
1.mu.m to 5 mm.
8. Transparent Substrate
Given as examples of the material used for a transparent substrate
are transparent glass substrates (ordinary visual light
transmittance of 50% or more) including inorganic oxide substrates
composed of such materials as soda lime glass, heat resistance
glass, quartz plate, and the like, and polymer substrates.
Because the thickness of the transparent substrate has no influence
on the angle of view, there are no limitations as to the thickness.
However, when the thickness is too great, it has some influence on
the light transmittance, so that the thickness is preferably in a
range from 1 .mu.m to 5 mm.
This transparent substrate is used for protecting the fluorescent
layer. The transparent substrate is also used for a support
substrate in the step of forming a film of the fluorescent layer.
Specifically, the above-mentioned inorganic oxide substrate is
applied to the transparent substrate using an ordinary transparent
adhesive used such for the sealing means, after the formation of
the film of the fluorescent layer. The resulting substrate may be
then combined with the support substrate on which the organic EL
device is laminated to seal the organic EL device.
9. Color Filter and Black Matrix
A color filter and black matrix used as required in the present
invention are formed, for example, by performing desired patterning
on desired positions of a material selected from known materials,
by photolithography or printing.
10. Action of the Present Invention
In the present invention, the fluorescent layer is disposed in the
position opposite to the organic EL device through the inorganic
oxide substrate so that gaseous substances such as organic
monomers, aqueous vapor, and the like which cause the device to
deteriorate are cut by the inorganic substrate, whereby the life of
the organic EL device and hence the life of the multi-color light
emission apparatus using the organic EL device can be improved.
Generally, fluorescent layers which each absorb light of one color
emitted from the organic EL device are separately disposed on the
same plane to obtain light emission of a plurality of colors such
as RGB primary colors or the like. The present invention uses the
transparent inorganic oxide substrate which is disposed on the
fluorescent layer facing the organic EL device whereby the
above-mentioned effects are expected. Also, the plate thickness of
the transparent inorganic substrate is in a range of from 1 .mu.m
to 200 .mu.m in the present invention, whereby not only are the
above-mentioned effects obtained, but also the absorption of the
light emitted from the organic EL device to a fluorescent layer
other than the desired fluorescent layer and light leakage from the
gap between the fluorescent layer and the organic EL device
decrease and hence light of a desired color can be produced,
ensuring improvement in the characteristics in the angle of view
for multi-color light emission.
Here, the fluorescent layer is used instead of a color filter
because compared with the case of using the color filter highly
efficient multi-color light emission can be expected as mentioned
above.
When a fluorescent layer is disposed on the outside of a
multi-color light emission apparatus, there are cases where the
fluorescent layer is damaged by handling and deteriorates from
external environmental factors such as water, oxygen, light, and
the like. In this invention, however, the protective layer of the
fluorescent layers is disposed on the fluorescent layer, thereby
protecting the fluorescent layer. Also, the transparent substrate
is used for protecting the fluorescent layer or for a support
substrate in the step of forming the fluorescent layer.
II. Multi-color Light Emission Apparatus (second invention) and
Process for Manufacturing Thereof (third invention)
The second invention of the present application, designated as
apparatus 20, has, specifically, a structure selected from the
structures (1) to (4) describe below from the above points of view.
These structures (1) to (4) are shown in FIGS. 9-12. Incidentally,
a fluorescent layer may convert the light emitted from the organic
EL device into light of a wave length longer than that of the light
emitted from the organic EL device. The converted color is not
limited to the following red or green color.
(1) Transparent support substrate 11/fluorescent layer 3R for
converting into red color (hereinafter called "red color conversion
fluorescent layer"), fluorescent layer 3G for converting into green
color (hereinafter called "green color conversion fluorescent
layer")/transparent and electrically insulating inorganic oxide
layer 12/organic EL device 1 (transparent electrode 1a/organic
compound layer 1b/electrode 1c);
(2) Transparent support substrate 11/red color conversion
fluorescent layer 3R, green color conversion fluorescent layer
3G/adhesive layer 13/transparent and electrically insulating
inorganic oxide layer 12/organic EL device 1 (transparent electrode
1a/organic compound layer 1b/electrode 1c);
(3) Transparent support substrate 11/red color conversion
fluorescent layer 3R, green color conversion fluorescent layer
3G/protective layer of the fluorescent layers (transparent flat
film) 7/adhesive layer 13/transparent and electrically insulating
inorganic oxide layer 12/organic EL device 1 (transparent electrode
1a/organic compound layer 1b/electrode 1c); and
(4) Transparent support substrate 11/red color conversion
fluorescent layer 3R, green color conversion fluorescent layer
3G/protective layer of the fluorescent layers (transparent flat
film) 7/transparent and electrically insulating inorganic oxide
layer 12/organic EL device 1 (transparent electrode 1a/organic
compound layer 1b/electrode 1c).
A red color filter and a green color filter may be assembled
between the red color conversion fluorescent layer 3R and the
transparent substrate, and between the green color conversion
fluorescent layer 3G and the transparent substrate respectively,
thereby adjusting colors of light of a red color and of a green
color to improve these color purities.
A blue color filter 14 may be disposed in parallel and between the
red color conversion fluorescent layer 3R and the green color
conversion fluorescent layer 3G, thereby adjusting the colors of
light emitted from the organic EL device to improve the color
purities.
Also, as shown in FIG. 13, a black matrix 9b may be disposed at
least in a space between the fluorescent layers 3R and 3G, and/or
the color filter 14 to cut leakage of light emitted from the
organic EL device 1 and thereby to improve the visibility of
multi-color light emission.
Further, as shown in FIG. 14, the transparent and electrically
insulating inorganic oxide layer 12 may be composed of two layers,
an upper inorganic oxide layer and a lower inorganic oxide layer so
that elution of inorganic ions from the lower inorganic oxide layer
(for example, soda-lime glass) is restrained by the upper inorganic
oxide layer to protect the organic EL device from the eluted
ions.
The thickness of the transparent and electrically insulating
inorganic oxide layer 12 is defined in a range of from 0.01 .mu.m
to 200 .mu.m. If the thickness of the transparent and electrically
insulating inorganic oxide layer is not larger than 0.01 .mu.m, it
is near that of a monolayer of an inorganic oxide particle and
hence deteriorative gas generated from organic compounds of the
lower fluorescent layer, protective layer, and the like never
cut.
On the other hand, if the thickness of the transparent and
electrically insulating layer exceeds 200 .mu.m, the light emitted
from the organic EL device leaks from the gap between the inorganic
oxide layer and the fluorescent layers 3R, 3G so that the angle of
view for multi-color light emission narrows, leading to a reduction
in practicability, although this depends on the fineness of the
fluorescent layers 3R and 3G.
The multi-color light emission apparatus of the second invention
and the process of the third invention for manufacturing same in
the present application are now illustrated for every structural
element in detail. Materials used for the structural elements are
not limited to the essential materials illustrated in the following
descriptions. Also, details common with those in the first
invention are omitted as far as possible to avoid redundancies.
1. Organic EL Device
The organic EL device of this invention is similar to that used in
the first invention.
(a) Anode
Materials similar to those used in the first invention can be used
as the materials for the anode.
(b) Emitting layer
Materials similar to those used in the first invention can be used
as the materials for an emitting layer.
(c) Positive hole injecting layer
Materials to those used in the first invention can be used as the
materials for a positive hole injecting layer.
(d) Electron Injecting Layer
Materials similar to those used in the first invention can be used
as the materials for an electron injecting layer.
(e) Cathode
Materials similar to those used in the first invention can be used
as the materials for a cathode.
(f) Manufacture of Organic EL Device(example)
The organic EL device used in this invention can be manufactured in
the same manner as in the first invention.
2. Transparent Support Substrate
A transparent support substrate used in the present invention is
preferably a transparent material (visible light transmittance of
50% or more) such as, for example, a glass plate, plastic plate
(polycarbonate, acryl, or the like), plastic film (polyethylene
terephthalate, polyether sulfide, or the like), quartz plate, or
the like. There are no limitations as to the thickness of the
support substrate to the extent that it can reinforce a thin
transparent glass plate to be laminated subsequently without camber
and distortion.
3. Fluorescent Layer
Materials similar to those used in the first invention can be used
as the materials for a fluorescent layer.
4. Transparent and Electrically Insulating Inorganic Oxide
Layer
A transparent and electrically insulating inorganic oxide layer
used in the present invention can be formed by laminating it on the
fluorescent layer, or a protective layer of the fluorescent layers
or transparent adhesive layer, such as described below, for
example, by vapor deposition, sputtering, dipping, spin-coating,
roll-coating, casting, anodic oxidation of metal film, or the
like.
The transparent and electrically insulating inorganic oxide layer
may be formed of either one layer or two layers. With the two layer
structure composed of an upper inorganic oxide layer and a lower
inorganic oxide layer, elution of inorganic ions from the lower
inorganic oxide layer (for example, soda-lime glass) is restrained
by the upper inorganic oxide layer to protect the organic EL device
from the eluted ions.
Examples of the materials used for the transparent and electrically
insulating inorganic oxide layer include silicon oxide (SiO.sub.2),
aluminum oxide (Al.sub.2 O.sub.3), titanium oxide (TiO.sub.2),
yttrium oxide (Y.sub.2 O.sub.3), germanium oxide (GeO.sub.2), zinc
oxide (ZnO), magnesium oxide (MgO), calcium oxide (CaO), boron
oxide (B.sub.2 O.sub.3), strontium oxide (SrO), barium oxide (BaO),
lead oxide (PbO), zirconium oxide (ZrO.sub.3), sodium oxide
(Na.sub.2 O), lithium oxide (Li.sub.2 O), potassium oxide (K.sub.2
O), and the like. Among these, silicon oxide, aluminum oxide, and
titanium oxide are preferable, since the transparency of the layer
(film) thereof is high and the film formation temperature is
comparatively low (250.degree. C. or less), hence the fluorescent
layer or the protective layer deteriorates little.
Also, as the transparent and electrically insulating inorganic
oxide layer, it is more preferable to use a glass plate or a glass
plate product made by forming a film of one or more compounds
selected from a group consisting of silicon oxide, aluminum oxide,
titanium oxide, and the like on at least one of the surface or back
face of a transparent and insulating glass plate. A low temperature
(150.degree. C. or less) operation allowing this glass plate or
glass plate product to be applied to the fluorescent layer or the
protective layer can be performed so that these layers never
entirely deteriorate. Also, the glass plate can especially cut out
aqueous vapor, oxygen, deteriorating gases such as monomer gas and
the like in an efficient manner.
Compositions of the glass plate are exemplified in Tables 1 and 2.
Among these, typical examples are sodalime glass, barium-strontium
containing-glass, lead glass, aluminosilicate glass, borosilicate
glass, barium borosilicate glass, and the like. Here, the
electrically insulating inorganic oxide layer may have a
composition containing mainly an inorganic oxide and may contain a
nitride (for example, Si.sub.3 N.sub.4) or fluoride (for example,
CaF.sub.2) It is preferable that the thickness of the electrically
insulating inorganic oxide layer be from 0.01 .mu.m to 200 .mu.m,
though there are no limitations as to the thickness to the extent
that it acts as an obstacle to the light emission of the organic EL
device. The glass plate or the glass plate product made by forming
a film of one or more compounds selected from a group consisting of
silicon oxide, aluminum oxide, titanium oxide, and the like on at
least one of the surface or back face of a transparent and
insulating glass plate has preferably a thickness of from 1 .mu.m
to 200 .mu.m in consideration of the accuracy and strength of a
plate glass.
The reason that inorganic oxide compounds including the glass plate
are desired is specifically because electro conductive and
transparent inorganic materials such as ITO (indium tin oxides),
which are often used, can be adopted as a transparent electrode
(anode) of the organic EL device and also because these have
excellent mutual affinity and adhesion.
Here, aqueous vapor, oxygen, and gas from organic compounds such as
monomers and the like exhibit the problem of a reduction in the
light emission life of the organic EL device. Therefore, it is
necessary for the transparent and electrically insulating inorganic
oxide layer to possess characteristics that do not cause generation
of aqueous vapor, oxygen, and gases of organic compounds such as
monomers and the like and wherein the external intrusion of these
harmful compounds can be prevented.
Specifically, the water content of the inorganic oxide layer is
measured by thermal analysis (DTA (Differential Thermal Analysis)
and DSC (Differential Scanning Calorimeter)). Also, the gas
permeability of the inorganic oxide layer for aqueous vapor and for
oxygen is measured according to a test method for permeability of
JIS K7126 and the like. If, especially, the water content is 0.1%
by weight or less and the gas permeability is 10.sup.-13
cccm/cm.sup.2 scmHg or less, reduction in the light emission life
of the organic EL device, indicated by generation of dark spots can
be prevented.
TABLE 1 ______________________________________ Glass composition
type ______________________________________ 1) R.sub.2
O--R'O--SiO.sub.2 Na.sub.2 O--CaO/MgO--SiO.sub.2 (soda-lime glass)
Na.sub.2 O/K.sub.2 O--BaO/SrO--SiO.sub.2 Na.sub.2 O/K.sub.2
O--CaO/ZnO--SiO.sub.2 2) R.sub.2 O--PbO--SiO.sub.2 K.sub.2
O/Na.sub.2 O--PbO--SiO.sub.2 (lead glass) 3) R.sub.2 O--B.sub.2
O.sub.3 --SiO.sub.2 Na.sub.2 O--B.sub.2 O.sub.3 --SiO.sub.2
(borosilicate glass) K.sub.2 O--B.sub.2 O.sub.3 --SiO.sub.2 4)
R'O--B.sub.2 O.sub.3 --SiO.sub.2 PbO--B.sub.2 O.sub.3 --SiO.sub.2
PbO/ZnO--B.sub.2 O.sub.3 --SiO.sub.2 PbO--B.sub.2 O.sub.3
--SiO.sub.2 + filler ZnO--B.sub.2 O.sub.3 --SiO.sub.2 5)
R'O--Al.sub.2 O.sub.3 --SiO.sub.2 CaO/MgO--Al.sub.2 O.sub.3
--SiO.sub.2 (aluminosilicate glass) MgO--Al.sub.2 O.sub.3
--SiO.sub.2 PbO/ZnO--Al.sub.2 O.sub.3 --SiO.sub.2 6) R.sub.2
O--Al.sub.2 O.sub.3 --SiO.sub.2 Li.sub.2 O--Al.sub.2 O.sub.3
--SiO.sub.2 Na.sub.2 O--Al.sub.2 O.sub.3 --SiO.sub.2 7)
R'O--TiO.sub.2 --SiO.sub.2 BaO--TiO.sub.2 --SiO.sub.2 8) R.sub.2
O--ZrO.sub.2 --SiO.sub.2 Na.sub.2 O/Li.sub.2 O--ZrO.sub.2
--SiO.sub.2 9) R'O--P.sub.2 O.sub.5 --SiO.sub.2 CaO--P.sub.2
O.sub.5 --SiO.sub.2 10) R'O--SiO.sub.2 CaO/BaO/PbO--SiO.sub.2 11)
SiO.sub.2 12) R.sub.2 O--R'O--B.sub.2 O.sub.3 Li.sub.2
O--BeO--B.sub.2 O.sub.3 13) R'O--R".sub.2 O.sub.3 --B.sub.2 O.sub.3
CaO/BaO--Al.sub.2 O.sub.3 --B.sub.2 O.sub.3 CaO/PbO--Lu.sub.2
O.sub.3 --B.sub.2 O.sub.3 14) R.sub.2 O--Al.sub.2 O.sub.3 --P.sub.2
O.sub.5 K.sub.2 O--Al.sub.2 O.sub.3 --P.sub.2 O.sub.5 15)
R'O--Al.sub.2 O.sub.3 --P.sub.2 O.sub.5 BaO/CaO--Al.sub.2 O.sub.3
--P.sub.2 O.sub.5 ZnO--Al.sub.2 O.sub.3 --P.sub.2 O.sub.5
______________________________________ R: monovalent element, R':
bivalent element, R": trivalent element
TABLE 2 ______________________________________ Composition
Classification (shown as a unary system-ternary system
______________________________________ 1 Simple oxide SiO.sub.2,
B.sub.2 O.sub.3, GeO.sub.2, As.sub.2 O.sub.3 2 Silicate Li.sub.2
O--SiO.sub.2, Na.sub.2 O--SiO.sub.2, K.sub.2 O--SiO.sub.2
MgO--SiO.sub.2, CaO--SiO.sub.2, BaO--SiO.sub.2, PbO--SiO.sub.2
Na.sub.2 O--CaO--SiO.sub.2 Al.sub.2 O.sub.3 --SiO.sub.2 3 Borate
Li.sub.2 O--B.sub.2 O.sub.3, Na.sub.2 O--B.sub.2 O.sub.3, K.sub.2
O--B.sub.2 O.sub.3 MgO--B.sub.2 O.sub.3, CaO--B.sub.2 O.sub.3,
PbO--B.sub.2 O.sub.3 Na.sub.2 O--CaO--B.sub.2 O.sub.3,
ZnO--PbO--B.sub.2 O.sub.3 Al.sub.2 O.sub.3 --B.sub.2 O.sub.3,
SiO.sub.2 --B.sub.2 O.sub.3 4 Phosphate Li.sub.2 O--P.sub.2
O.sub.5, Na.sub.2 O--P.sub.2 O.sub.5 MgO--P.sub.2 O.sub.5,
CaO--P.sub.2 O.sub.5, BaO--P.sub.2 O.sub.5 K.sub.2 O--BaO--P.sub.2
O.sub.5 Al.sub.2 O.sub.3 --P.sub.2 O.sub.5, SiO2--P.sub.2 O.sub.5,
B.sub.2 O.sub.3 --P.sub.2 O.sub.5 V.sub.2 O.sub.5 --P.sub.2
O.sub.5, Fe.sub.2 O.sub.3 --P.sub.2 O.sub.5, WO.sub.3 --P.sub.2
O.sub.5 5 Germanate glass Li.sub.2 O--GeO.sub.2, Na.sub.2
O--GeO.sub.2, K.sub.2 O--GeO.sub.2 B.sub.2 O.sub.3 --GeO.sub.2,
SiO.sub.2 --GeO.sub.2 6 Tungstate Na.sub.2 O--WO.sub.3, K.sub.2
O--WO.sub.3 7 Molybdate Na.sub.2 O--MoO.sub.3, K.sub.2
O--MoO.sub.3, L.sub.2 O--MoO.sub.3 8 Tellurate Na.sub.2
O--TeO.sub.2 9 Borosilicate Na.sub.2 O--B.sub.2 O.sub.3 --SiO.sub.2
10 Aluminosilicate Na.sub.2 O--Al.sub.2 O.sub.3 --SiO.sub.2,
CaO--Al.sub.2 O.sub.3 --SiO.sub.2 11 Aluminoborate CaO--Al.sub.2
O.sub.3 --B.sub.2 O.sub.3, ZnO--Al.sub.2 O.sub.3 --B.sub.2 O.sub.3
12 Aluminoborosilicate Na.sub.2 O--Al.sub.2 O.sub.3 --B.sub.2
O.sub.3 --SiO.sub. 2 13 Fluoride BeF.sub.2, NaF--BeF.sub.2
ZrF.sub.4 --BaF.sub.2 --ThF.sub.4, GdF.sub.3 --BaF.sub.2
--ZrF.sub.4 14 Phosphorus fluoride Al(PO.sub.3).sub.3 --AlF.sub.3
--NaF--CaF.sub.2 15 Oxyhalogenide Ag.sub.2 O--AgI--P.sub.2 O.sub.5
16 Oxynitride MgO--Al.sub.2 O.sub.3 --AlN--SiO.sub.2
______________________________________
5. Protective Layer of the Fluorescent Layers (transparent flat
film)
Materials similar to those of the first invention may be used as a
protective layer of the fluorescent layers (transparent flat
film).
However, the thickness of the protective layer in the second
invention is preferably from 0.5 .mu.m to 100 .mu.m approximately.
It is desirable that the thickness of the protective layer be as
small as possible to reduce light leakage from the gap between the
fluorescent layer and the organic EL device with respect to the
light emitted from the organic EL device. However, if the film
thickness is too small, no effect of protecting the fluorescent
layer can be obtained, depending on the type of adhesive.
6. Transparent Adhesive Layer
It is desirable that a transparent adhesive layer, which is used as
required in the present invention, be used in the case of adopting
the substrate produced by forming the fluorescent layer (including
a color filter, black matrix, and protective layer as required) on
the transparent support substrate and also, especially, in the case
of adopting a glass plate as the inorganic oxide layer. A material
which is transparent (visible transmittance of 50% or more), at
least in the portion where the light emitted from the organic EL
device is transmitted is preferable as the material used for the
transparent adhesive layer.
Specifically given as examples of the adhesive are photocurable or
heat-curable adhesives having a reactive vinyl group of an acrylic
acid type oligomer and methacrylic acid type oligomer; and
moisture-curable adhesives such as 2-cyanoacrylate and the like.
Also, heat-curable and chemical-curable type (two liquid mixture
type) adhesives such as an epoxy or the like can be used.
An adhesive having a low viscosity (about 100 cp or less) ensures
that there is no formation of air bubbles when it is applied and
hence uniform application is allowable. However, the low viscosity
adhesive dissolves and erodes the fluorescent layer depending on
the conditions so that it is necessary to laminate the above
protective layer on the fluorescent layer. An adhesive having a
high viscosity (about 100 cp or more) is scarcely dissolved, and
erodes the fluorescent layer so that there is the case where the
protective layer of the fluorescent layers is not required. On the
contrary, this causes formation of air bubbles, hence uniform
application can be achieved only with difficulty. The necessity of
providing the protective layer of the fluorescent layers may be
determined according to the characteristics of the adhesive.
The adhesive is applied on a substrate, on which the fluorescent
layer (including a color filter, black matrix, and protective layer
as required) is formed to form a film by spin-coating, roll
coating, casting, or the like. Then, a glass plate, on which the
transparent electrode has been formed or is to be formed, or a
glass plate product made by forming a film of one or more compounds
selected from a group consisting of silicon oxide, aluminum oxide,
titanium oxide, and the like on at least one of the surface or back
face of a transparent, insulating glass plate is applied to the
substrate through the adhesive film by means of light (UV rays),
heat (up to 150.degree. C.), chemical mixing, or the like according
to the specification of the adhesive.
It is preferable that the thickness of the adhesive layer be in the
order of 0.1 .mu.m to 200 .mu.m. It is desirable that the thickness
of the protective layer be as small as possible to reduce light
leakage from the gap between the fluorescent layer and the organic
EL device with respect to the light emitted from the organic EL
device, thereby improving the characteristics of the angle of view
. However, if the film thickness is too small, there is the case
where uniform application can be attained only with difficulty due
to unevenness between the fluorescent layers.
7. Color Filter and Black Matrix
A color filter and a black matrix used as required in the present
invention are formed, for example, by appropriately patterning
desired positions of a material selected from known materials by
photolithography or printing.
8. Action of the Present Invention
In the present invention with the above structure, the inorganic
oxide layer with a thickness of from 0.01 to 200 .mu.m cuts out
aqueous vapor, oxygen, or gaseous substances such as organic
monomers, which are considered to adhere to or to be contained
originally in small amounts in organic compounds forming the lower
fluorescent layer or the protective layer of the fluorescent layers
or which are considered to be generated by the fluorescent layer or
the protective layer by heat when the organic EL device emits
light. Hence, the causes of deterioration of the organic EL device
can be reduced. Especially in the case of using a glass plate as
the inorganic oxide layer, such deteriorative gaseous substances
can be prevented to a high degree, resulting in improvement in
storage stability and in the light emission life of the multi-color
light emission apparatus.
Also, the film thickness of the inorganic oxide layer is 200 .mu.m
or less in the present invention, so that undesirable light
emission caused by absorption of the light emitted from the organic
EL device by a fluorescent layer other than the desired fluorescent
layer and light leakage from the gap between the fluorescent layer
and the organic EL device decrease, hence light of a desired color
could be produced, resulting in improvement in the characteristics
of the angle of view for multi-color light emission.
Also, the inorganic oxide layer and the transparent electrode
(usually composed of ITO (indium or tin oxide) provide a higher
quality adhesion than those composed of organic compounds, thereby
facilitating the patterning (usually by photolithography) of the
transparent electrode.
Also, in the present invention, the transparent adhesive layer is
placed on the boundary of the inorganic oxide layer on the side of
the fluorescent layer. Especially in the case where the inorganic
oxide layer located at the boundary of the transparent electrode of
the organic EL device on the side of the fluorescent layer is
composed of a glass plate, adhesion between the organic EL device
and the fluorescent layer is enhanced and the organic EL device and
the fluorescent layer are integrated. Further, when the transparent
protective layer of the fluorescent layers is arranged between the
adhesive layer and the fluorescent layer, the fluorescent layer is
protected from being dissolved and eroded by the adhesive layer.
The protective layer ensures that the uneven film thickness of the
fluorescent layers to be separately disposed on the same plane is
moderated, the deformation of the inorganic oxide layer on the
fluorescent layer is reduced, and defects such as cracking and the
like in the inorganic oxide layer or the transparent electrode
decrease.
If a thin glass plate with a thickness of from 1 .mu.m to 200 .mu.m
is used as the inorganic oxide layer, it is difficult to form an
organic electroluminescent device directly on the glass plate in a
stable manner since the thin film-glass plate which is physically
fragile tends to be cambered and distorted. However, in the process
of the present invention, this thin glass plate is combined with
the transparent support substrate on which the fluorescent layer
and the protective layer of the fluorescent layers are laminated
via the adhesive layer. Also, the organic electroluminescence
devices are laminated in order, so that the multi-color light
emission apparatus can be produced in a stable manner.
EXAMPLES
The present invention will be explained in more detail by way of
examples, which are not intended to be limiting of the present
invention.
Example 1
An methacrylate type resist containing carbon black (CK 2000,
manufactured by Fuji Hunt Electronics Technology Co., Ltd.) was
applied by spin-coating to one the faces of a support substrate
(Glass 7059, manufactured by Corning Co., Ltd.) with dimensions of
25 mm.times.75 mm.times.1.1 mm (thickness), which was baked at
200.degree. C. to form a black film (about 2 .mu.m thickness).
Next, the face opposite to the black film of this substrate was
washed with IPA and further irradiated with UV light. Then, the
substrate was secured to a substrate holder of a vapor deposition
unit (manufactured by ULVAC Corporation). As materials for vapor
deposition, MTDATA and NPD for a positive hole injecting layer,
DPVBi for an emitting material, and Alq for an electron injecting
layer were placed in a resistance heating molybdenum boat. Ag was
attached to a tungsten filament as a second metal for an electrode
(cathode), and Mg was attached to the molybdenum boat as an
electron injecting metal for an electrode (cathode).
After that, the pressure in a vacuum vessel was reduced to
5.times.10.sup.-7 torr and then the above materials were
sequentially laminated in the following order through a mask which
enabled film to be formed in a range of 10 mm.times.60 mm. A vacuum
was maintained during the steps between a step of forming
electrodes and a step of forming the positive hole injecting layer
by one evacuating operation.
First, Mg and Ag were vapor-deposited as the electrode
simultaneously at vapor deposition rates of 1.3-1.4 nm/s and 0.1
nm/s respectively to a film thickness of 200 nm. Then, an electron
injecting layer was formed by depositing Alq at a vapor deposition
rate of 0.1-0.3 nm/s to a film thickness of 20 nm. Next, an
emitting layer was formed by depositing DPVBi at a vapor deposition
rate of 0.1-0.3 nm/s to a film thickness of 50 nm. Finally, a
positive hole injecting layer was formed by depositing NPD at a
vapor deposition rate of 0.1-0.3 nm/s to a film thickness of 20 nm
and also depositing MTDATA at a vapor deposition rate of 0.1-0.3
nm/s to a film thickness of 200 nm.
Next, the substrate was transferred to a sputtering apparatus. A
transparent electrode (anode) film of ITO (indium oxide or tin
oxide) with a thickness of 120 nm and a surface resistance of 20
.OMEGA./.quadrature. was formed on this substrate at room
temperature through a mask which enabled a film to be formed of an
area of 10 mm.times.60 mm to create an organic EL device. Here, the
mask was lifted so that the ranges of the electrodes and
transparent electrode were crossed (in a range of 10 mm.times.55
mm) and the terminal of each electrode could be taken.
Next, an epoxy, two-liquid mixing type adhesive (Araldite,
manufactured by Ciba Geigy Co., Ltd.) was applied to the
peripheries of the crossed portions (10 mm.times.55 mm) at a width
of 1 mm approximately with partial slits using a dispenser to form
a substrate A.
Then, a transparent inorganic oxide substrate (barium borosilicate
glass) (substrate B) of 25 mm.times.75 mm.times.1.1 mm (thickness)
was applied to the substrate A and the adhesive was cured. After
that, hydrocarbon fluoride (Fluorinert, manufactured by Sumitomo 3M
Corp.) was injected under a nitrogen atmosphere, using an injection
needle, through the above slits into gaps between the support
substrate (substrate A.) and the applied substrate (substrate B).
Then, the same adhesive was filled into the slits in the cured
adhesive and cured.
Next, characters EL with a width of 1 mm were printed on the
substrate within the portion corresponding to the crossed portion
(a range of 10 mm.times.55 mm) through a screen board using an ink
(viscosity 8,000 cp) produced by dissolving coumarin 6/polyvinyl
chloride resin (molecular weight of 20,000) in cyclohexanone in the
coumarin 6 concentration of 0.03 mol/kg (film). The characters were
air-dried to prepare a fluorescent pattern of the characters EL (15
.mu.m thickness).
A multi-color light emission apparatus composed of the organic EL
device was manufactured in this manner as shown in FIG. 1. When a
d.c. voltage of 8 V was applied between the transparent electrode
(anode) and the electrode (cathode) of the multi-color light
emission apparatus, the crossed portions of the transparent
electrodes (anodes) and the electrodes (cathodes) emitted light.
The luminance of the light viewed from the portion lacking the
fluorescent layer was 100 cd/m.sup.2. The CIE chromaticity
coordinates (JIS Z 8701) were as follows: x=0.15, y=0.15. Light of
a blue color was detected.
Also, the luminance of the light viewed from the fluorescent layer
provided with the patterned characters EL was 120 cd/m.sup.2 and
the CIE chromaticity coordinates were as follows: x=0.28, y=0.62.
Light of a yellowish green color was detected.
The multi-color light emission apparatus was allowed to stand in
the atmosphere for two weeks. As a result, the multi-color light
emission apparatus maintained uniform light emission without
changes in luminance and chromaticity and also without dark spots
appearing as deterioration of the device progressed.
Example 2
A support substrate (substrate A) provided with an organic EL
device was combined with a transparent inorganic oxide substrate
(substrate B) in the same manner as in Example 1 to form a
substrate containing a gap filled with hydrocarbon fluoride. Next,
the characters EL with a width of 1 mm were printed on the
substrate within the portion corresponding to the crossed portion
(range 10 mm.times.55 mm) of an electrode and a transparent
electrode through a screen board using an ink (viscosity 8,000 cp)
produced by dissolving 43% (for film) by weight of a pigment
containing rhodamine/polyvinyl chloride resin (molecular weight
20,000) in cyclohexanone. The characters were air-dried to prepare
a fluorescent pattern of the characters EL (20 .mu.m
thickness).
A multi-color light emission apparatus composed of the organic EL
device was manufactured in this manner as shown in FIG. 1. When a
d.c. voltage of 8 V was applied between the transparent electrode
(anode) and the electrode (cathode) of the multi-color light
emission apparatus, the crossed portions of the transparent
electrodes and the electrodes emitted light. The luminance of the
light viewed from the portion lacking the fluorescent layer was 100
cd/m.sup.2. The CIE chromaticity coordinate (JIS Z 8701) was as
follows: x=0.15, y=0.15. Light of a blue color was detected.
Also, the luminance of the light viewed from the fluorescent layer
provided with the patterned characters EL was 30 cd/m.sup.2 and the
CIE chromaticity coordinates were as follows: x=0.60, y=0.31. Light
of a red color was detected.
The multi-color light emission apparatus was allowed to stand in
the atmosphere for two weeks. As a result, the multi-color light
emission apparatus maintained uniform light emission without
changes in luminance and chromaticity coordinate and also without
dark spots appearing as deterioration of the device progressed.
Example 3
An methacrylate type resist containing carbon black (CK 2000,
manufactured by Fuji Hunt Electronics Technology Co., Ltd.) was
applied by spin-coating to one face of a support substrate (Glass
7059, manufactured by Corning Co., Ltd.) of 100 mm.times.100
mm.times.1.1 mm (thickness), which was baked at 200.degree. C. to
form a black film with a thickness of about 2 .mu.m.
Next, the face opposite to the black film of this substrate was
washed with IPA and further irradiated with UV light. Then, the
substrate was secured to a substrate holder of a vapor deposition
unit (manufactured by ULVAC Corporation). As materials for vapor
deposition, MTDATA and NPD for a positive hole injecting layer,
DPVBi for a emitting material, and Alq for an electron injecting
layer were placed in a resistance heating molybdenum boat. Ag as a
second metal for an electrode (cathode) was attached to a tungsten
filament, and Mg as an electron injecting metal for an electrode
(cathode) was attached to the molybdenum boat.
After that, the pressure in a vacuum vessel was reduced to
5.times.10.sup.-7 torr. First, a film with a pattern of an
electrode was formed using a mask capable of transferring a stripe
pattern of an 1.5 mm pitch (1.4 mm lines and 0.1 mm gaps) in a
range of 72 mm.times.72 mm. Next, films of layers from an electron
injecting layer to a positive hole injecting layer were formed
using a mask enabling a film to be formed in a range of 72
mm.times.72 mm. A vacuum was maintained during the steps between
the step of forming the electrodes and the step of forming the
positive hole injecting layer by one evacuating operation.
First, Mg and Ag were simultaneously vapor-deposited as the
electrodes at vapor deposition rates of 1.3-1.4 nm/s and 0.1 nm/s
respectively to a film thickness of 200 nm. Then, an electron
injecting layer was formed by depositing Alq at a vapor deposition
rate of 0.1-0.3 nm/s to a film thickness of 20 nm. Next, an
emitting layer was formed by depositing DPVBi at a vapor deposition
rate of 0.1-0.3 nm/s to a film thickness of 50 nm. Finally, a
positive hole injecting layer was formed by depositing NPD at a
vapor deposition rate of 0.1-0.3 nm/s to a film thickness of 20 nm
and also depositing MTDATA at a vapor deposition rate of 0.1-0.3
nm/s to a film thickness of 400 nm.
Next, the substrate was transferred to a sputtering apparatus. A
film of a transparent electrode (anode) of ITO with a thickness of
120 nm and a surface resistance of 20 .OMEGA./.quadrature. was
formed on this substrate at room temperature through a mask which
enabled a solid film with a stripe pattern of 4.5 mm pitch (4.0 mm
lines, 1.0 mm gaps) to be formed in a range of 72 mm.times.72 mm,
to form an organic EL device. Here, the mask was located so that
the ranges of the electrodes and transparent electrodes were
crossed and the terminal of each electrode could be taken.
Next, an epoxy, two-liquid mixing type adhesive (Araldite,
manufactured by Ciba Geigy Co., Ltd.) was applied to the
peripheries of the crossed portions (a range of 72 mm.times.72 mm)
at a width of 1 mm approximately with partial slits using a
dispenser to form a substrate C.
Then, a transparent inorganic oxide substrate (barium borosilicate
glass) (substrate D) of 100 mm.times.100 mm.times.0.15 mm was
applied to the substrate C and the adhesive was cured. After that,
hydrocarbon fluoride (Fluorinert, manufactured by Sumitomo 3M
Corp.) was injected under a nitrogen atmosphere, using an injection
needle, through the above slits into a gap between the support
substrate (substrate C) and the applied substrate (substrate D).
Then, the same adhesive was filled into the slits in the cured
adhesive and cured.
Next, a pattern of a fluorescent layer A with a thickness of 15
.mu.m was printed by screen printing on the substrate using an ink
(viscosity 8,000 cp) produced by dissolving coumarin 6/polyvinyl
chloride resin (molecular weight 20,000) in cyclohexanone in the
coumarin 6 concentration of 0.03 mol/kg (film) through a screen
board which enabled a stripe pattern of 1.4 mm lines and 3.1 mm
gaps to be formed after aligning with the electrodes (cathodes) of
the organic EL device, followed by air-drying.
Next, a pattern of a fluorescent layer B with a thickness of 20
.mu.m was printed by screen printing on the substrate using an ink
(viscosity 8,000 cp) produced by dissolving 43% (for film) by
weight of a pigment containing rhodamine/polyvinyl chloride resin
(molecular weight 20,000) in cyclohexanone through a screen board
which enabled a stripe pattern of 1.4 mm lines and 3.1 mm gaps to
be formed after lifting the pattern 1.5 mm from the pattern of the
fluorescent layer A in a direction perpendicular to the stripe,
followed by air-drying.
A multi-color light emission apparatus composed of the organic EL
device (dot matrix type) was manufactured in this manner as shown
in FIG. 4. When a d.c. voltage of 8 V was applied between the anode
and the cathode of the multi-color light emission apparatus, the
crossed portions of the transparent electrodes (anodes) and the
electrodes (cathodes) emitted light. The luminance of the light
viewed from the portion lacking the fluorescent layer was 100
cd/m.sup.2. The CIE chromaticity coordinate (JIS Z 8701) was as
follows: x=0.15, y=0.15. Light of a blue color was detected.
Also, the luminance of the light viewed from the fluorescent layer
A was 120 cd/m.sup.2 and the CIE chromaticity coordinates were as
follows: x=0.28, y=0.62. Light of a yellowish green color was
detected.
On the other hand, the luminance of the light viewed from the
fluorescent layer B was 30 cd/m.sup.2 and the CIE chromaticity
coordinates were as follows: x=0.60, y=0.31. Light of a red color
was detected.
The multi-color light emission apparatus was allowed to stand in
the atmosphere for two weeks. As a result, the multi-color light
emission apparatus maintained uniform light emission without
changes in luminance and chromaticity coordinate and also without
dark spots appearing as deterioration of the device progressed.
Also, the angle of view defined by the range in which leakage of
light (mono-chromatic light) was not confirmed was .+-.60.degree.
which was a practical level.
Example 4
A coating agent composed of an aqueous polyvinyl pyrrolidone
(molecular weight 360,000) solution was applied by spin-coating on
the fluorescent layer of the multi-color light emission apparatus
composed of the organic EL device manufactured in Example 1 and
air-dried to laminate a protective layer of the fluorescent layers
with a thickness of 10 .mu.m.
A multi-color light emission apparatus composed of the organic EL
device was manufactured in this manner as shown in FIG. 2. The
multi-color light emission apparatus was allowed to stand in the
atmosphere for two weeks. As a result, the multi-color light
emission apparatus maintained uniform light emission without
changes in luminance and chromaticity coordinates and also without
dark spots appearing as deterioration of the device progressed.
Also, because the protective layer was laminated, the fluorescent
layer was never damaged even if the fluorescent layer was contacted
by a nail and the handling, such as carrying, of the apparatus was
easy.
Example 5
An adhesive was applied to a substrate produced by forming an
organic EL device on a support substrate in the same manner as in
Example 3 to form a substrate X.
Separately, a pattern of a fluorescent layer A with a thickness of
15 .mu.m was printed by screen printing on a transparent substrate
(7059, manufactured by Corning Co., Ltd.) of 100 mm.times.100
mm.times.0.70 mm (thickness) using an ink (viscosity 8,000 cp)
produced by dissolving coumarin 6/polyvinyl chloride resin
(molecular weight 20,000) in cyclohexanone in the coumarin 6
concentration of 0.03 mol/kg (film) through a screen board which
enabled a stripe pattern of 1.4 mm lines and 3.1 mm gaps to be
formed after aligning with the location corresponding to electrodes
of the organic EL device, followed by baking at 120.degree. C.
Next, a pattern of a fluorescent layer B with a thickness of 20
.mu.m was printed by screen printing on the substrate using an ink
(viscosity 8,000 cp) produced by dissolving 43% (for film) by
weight of a pigment containing rhodamine/polyvinyl chloride resin
(molecular weight 20,000) in cyclohexanone through a screen board
which enabled a stripe pattern of 1.4 mm lines and 3.1 mm gaps to
be formed after lifting the pattern 1.5 mm from the pattern of the
fluorescent layer A in a direction perpendicular to the stripe,
followed by baking at 120.degree. C.
An aqueous polyvinyl pyrrolidone (molecular weight 360,000)
solution was applied by spin-coating to the substrate to laminate a
protective layer of the fluorescent layers with a thickness of 10
.mu.m. Next, 2-cyanoacrylate type adhesive (*Aron .alpha.,
manufactured by Toagosei Chemical Industry Co., Ltd.) was applied
to the entire substrate by casting to provide an inorganic oxide
substrate (aluminoborosilicate glass) of 100 mm.times.100
mm.times.0.05 mm (thickness) on the substrate to form a substrate
Y.
The substrate Y was applied to the above substrate X so that a 0.05
mm thickness substrate of the substrate Y faced the organic EL
device and the fluorescent layers A and B were aligned with the
electrodes of the organic EL device and the adhesive was cured.
After that, hydrocarbon fluoride (Fluorinate, manufactured by
Sumitomo 3M Corp.) was injected under a nitrogen atmosphere using
an injection needle, through slits in the cured adhesive into a gap
between the support substrate (substrate X) and the applied
substrate (substrate Y). Then, the same adhesive was filled into
the slits in the cured adhesive and cured.
The luminance and chromaticity coordinate of the light emitted in
the multi-color light emission apparatus, composed of the organic
EL device shown in FIG. 6 and designated as apparatus 10, which was
manufactured in this manner, were the same as those in Example 3.
Even if the multi-color light emission apparatus was allowed to
stand in the atmosphere for two weeks, the multi-color light
emission apparatus maintained uniform light emission without
changes in luminance and chromaticity coordinate and also without
dark spots as deterioration of the device progressed. Also, the
angle of view defined by the range in which leakage of light
(mono-chromatic light) emitted from the organic electroluminescence
device was not confirmed was .+-.70.degree. which was a practical
level.
Also, because the transparent substrate was laminated, the
fluorescent layer was never damaged even if the fluorescent layer
was contacted by a nail and the handling, such as carrying of the
apparatus, was easy.
Comparative Example 1
First, a substrate A was manufactured in the same manner as in
Example 1.
Next, characters EL with a width of 1 mm were printed on the
transparent substrate with dimension of 25 mm.times.75 mm.times.1.1
mm (thickness) within the portion corresponding to the crossed
portion (a range of 10 mm.times.55 mm) of an electrode and a
transparent electrode through a screen board using an ink
(viscosity 8,000 cp) produced by dissolving coumarin 6/polyvinyl
chloride resin (molecular weight 20,000) in cyclohexanone in the
coumarine 6 concentration of 0.03 mol/kg (film). The characters
were air-dried to prepare a fluorescent pattern of the characters
EL to form a substrate E.
The substrate E was applied to the above substrate A so that the
fluorescent layer of the substrate E faced the organic EL device
and the adhesive was cured. After that, hydrocarbon fluoride
(Fluorinert, manufactured by Sumitomo 3M Corp.) was injected under
a nitrogen atmosphere using an injection needle, through slits in
the cured adhesive into a gap between the support substrate
(substrate A) and the applied substrate (substrate E). Then, the
same adhesive was filled into the slits in the cured adhesive and
cured.
A multi-color light emission apparatus composed of the organic EL
device was manufactured in this manner as shown in FIG. 7. When a
d.c. voltage of 8 V was applied between the transparent electrode
(anode) and the electrode (cathode) of the multi-color light
emission apparatus, the crossed portions of the transparent
electrodes and the electrodes emitted light. The luminance and
chromaticity coordinates of each light viewed from the portion
lacking the fluorescent layer and from the characters EL were the
same as those in Example 1.
However, when the multi-color light emission apparatus was allowed
to stand in the atmosphere for two weeks, the luminance of the blue
light emitting portion decreased to 5 cd/m.sup.2 and the luminance
of the light viewed from the characters EL decreased to 7
cd/m.sup.2. Also, dark spots, appearing as deterioration of the
device progressed, increased, resulting in nonuniform light
emission. It was confirmed that when the fluorescent layer is
disposed so as to face the organic EL device contrary to Example 1,
the light emission life of the multi-color light emission apparatus
was greatly impaired.
Comparative Example 2
A substrate C was manufactured in the same manner as in Example
3.
A transparent inorganic oxide substrate (borosilicate glass)
(substrate F) of 100 mm.times.100 mm.times.0.30 mm thickness was
applied to the above substrate C. Then, a multi-color light
emission apparatus composed of an organic EL device (dot matrix
type) shown in FIG. 4 was formed in the same manner as in Example
3.
This multi-color light emission apparatus was allowed to emit light
to result in obtaining the same luminance and chromaticity as in
Example 3.
When the multi-color light emission apparatus was allowed to stand
in the atmosphere for two weeks, the multi-color light emission
apparatus maintained uniform light emission without changes in
luminance and chromaticity coordinates and also without dark spots
appearing as deterioration of the device progressed. However, the
angle of view defined by the range in which leakage of light
(mono-chromatic light) emitted from the organic electroluminescence
device was not confirmed was .+-.30.degree., so that there were
portions (angles) where the light color viewed from a normal sight
range differed from the emitted light color, exhibiting a problem
in practical use.
Example 6
A pattern of a fluorescent layer A with a thickness of 15 .mu.m was
printed by screen printing on a glass substrate (7059, manufactured
by Corning Co., Ltd.) of 100 mm.times.100 mm.times.1.1 mm
(thickness) as a transparent support substrate using an ink
(viscosity 8,000 cp) produced by dissolving coumarin 6/polyvinyl
chloride resin (molecular weight 20,000) in cyclohexanone in the
coumarin 6 concentration of 0.03 mol/kg (film) through a screen
board which enabled a stripe pattern of 1.4 mm lines and 3.1 mm
gaps to be formed, followed by baking at 120.degree. C. Next, a
pattern of a fluorescent layer B with a thickness of 20 .mu.m were
printed by screen printing on the substrate using an ink (viscosity
8,000 cp) produced by dissolving 43% (for film) by weight of a
pigment containing rhodamine/polyvinyl chloride resin (molecular
weight 20,000) in cyclohexanone through a screen board which
enabled a stripe pattern of 1.4 mm lines and 3.1 mm gaps to be
formed after lifting the pattern 1.5 mm from the pattern of the
fluorescent layer A in a direction perpendicular to the stripe,
followed by baking at 120.degree. C.
An aqueous solution of 20% by weight of polyvinyl alcohol
(molecular weight 50,000) was applied to the entire substrate
provided with the patterns of the fluorescent layers by
spin-coating. The substrate was baked at 80.degree. C. to prepare a
transparent protective layer of the fluorescent layers with a
thickness of 5 .mu.m.
Next, a photocurable transparent adhesive of epoxy type oligomer
(3102, manufactured by Three Bond corp.) was applied to the
protective layer by casting. The glass surface of a glass plate
(borosilicate glass) of 100 mm.times.100 mm.times.50 .mu.m
thickness as an insulating inorganic oxide layer, on which a film
of a transparent electrode (anode) of ITO (indium oxide or tin
oxide) with a thickness of 0.12 .mu.m and a surface resistance of
20 .OMEGA./.quadrature. was formed, was applied to the protective
layer. The substrate was irradiated with UV light through the ITO
surface at a dose of 3,000 mJ/cm.sup.2 (365 nm), followed by baking
at 80.degree. C.
A film of a novolak/quinonediazido type positive resist (HPR 204,
manufactured by Fuji Hunt Electronics Technology Co., Ltd.) was
laminated by spin-coating. After baking at 80.degree. C., the
substrate was placed on a proximity type exposure machine. Then,
the substrate was irradiated with light at a dose of 100
mJ/cm.sup.2 (365 nm) using a mask capable of transferring a stripe
pattern of 1.2 mm lines and 0.3 mm gaps after aligning the mask
with the fluorescent layers A and B.
The resist on the substrate was developed using an aqueous solution
of 2.38% by weight of TMAH (Tetra-Methyl Ammonium Hydroxide) and
post-baked at 130.degree. C. Then, the exposed ITO film was treated
by etching using aqueous hydrobromic acid and, finally, the
positive type resist was peeled off to prepare a pattern of the ITO
film which constitutes an anode of the organic EL device.
Next, this substrate was washed with IPA and further irradiated
with UV light. Then, the substrate was secured to a substrate
holder of a vapor deposition unit (manufactured by ULVAC
Corporation). As materials for vapor deposition, MTDATA and NPD for
a positive hole injecting layer, DPVBi for anemittingmaterial,
andAlq for an electron injecting layer, were placed in a resistance
heating molybdenum boat. Ag as a second metal for an electrode
(cathode) was attached to a tungsten filament, and Mg as an
electron injecting metal for an electrode (cathode) was attached to
the molybdenum boat.
After that, the pressure in a vacuum vessel was reduced to
5.times.10.sup.-7 torr and then the above materials were
sequentially laminated in the following order. A vacuum was
maintained during the steps between the step of forming the
positive hole injecting layer and the step of forming the cathode
by one evacuating operation. First, a positive hole injecting layer
was formed by depositing MTDATA at a vapor deposition rate of
0.1-0.3 nm/s to a film thickness of 200 nm and also depositing NPD
at a vapor deposition rate of 0.1-0.3 nm/s to a film thickness of
20 nm. Next, an emitting layer was formed by depositing DPVBi at a
vapor deposition rate of 0.1-0.3 nm/s to a film thickness of 50 nm.
Then, an electron injecting layer was formed by depositing Alq at a
vapor deposition rate of 0.1-0.3 nm/s to a film thickness of 20 nm.
Finally, Mg and Ag were vapor-deposited simultaneously as the
cathode at vapor deposition rates of 1.3-1.4 nm/s and 0.1 nm/s
respectively to a film thickness of 200 nm through a mask capable
of transferring a stripe pattern of 4 mm lines and 0.5 mm gaps
which is perpendicular to the stripe pattern of the anode composed
of ITO.
A multi-color light emission apparatus composed of the organic EL
device was manufactured in this manner as shown in FIG. 11. When a
d.c. voltage of 8 V was applied between the anode and the cathode
of the multi-color light emission apparatus, the crossed portions
of the anodes and cathodes emitted light. The luminance of the
light viewed from the portion lacking the fluorescent layer was 100
cd/m.sup.2. The CIE chromaticity coordinate (JIS Z 8701) was as
follows: x=0.15, y=0.15. Light of a blue color was detected.
On the other hand, the luminance of the light viewed from the
fluorescent layer A was 120 cd/m.sup.2 and the CIE chromaticity
coordinates were as follows: x=0.28, y=0.62. Light of a yellowish
green color was detected.
Also, the luminance of the light viewed from the fluorescent layer
B was 30 cd/m.sup.2 and the CIE chromaticity coordinates were as
follows: x=0.60, y=0.31. Light of a red color was detected.
The multi-color light emission apparatus manufactured in the above
manner was allowed to stand under a nitrogen stream for two weeks.
As a result, the multi-color light emission apparatus maintained
uniform light emission without changes in luminance and
chromaticity coordinates and also without dark spots appearing as
deterioration of the device progressed. Also, the angle of view
defined by the range in which leakage of light (mono-chromatic
light) emitted from the organic EL device was not confirmed was
60.degree., which was a practical level.
The water content of the glass substrate with a thickness of 50
.mu.m was 0.1% by weight or less and the gas permeability of the
glass substrate for aqueous vapor and for oxygen was 10.sup.-13
cccm/cm.sup.2 scmHg or less.
Example 7
A photocurable transparent adhesive of epoxy type oligomer (3112,
manufactured by Three Bond corp.) was applied, by casting, to the
substrate provided with the fluorescent layers A and B, which was
prepared in Example 6. The glass surface of a glass plate
(borosilicate glass) of 100 mm.times.100 mm.times.50 .mu.m
thickness as an insulating inorganic oxide layer on which a film of
a transparent electrode (anode) of ITO with a thickness of 0.12
.mu.m and a surface resistance of 20 .OMEGA./.quadrature. was
formed was applied to the substrate. The substrate was irradiated
with UV rays through the surface of ITO at a dose of 3,000
mJ/cm.sup.2 (365 nm), followed by baking at 80.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to prepare a multi-color
light emission apparatus composed of the organic EL device shown in
FIG. 10.
This multi-color light emission apparatus was allowed to emit light
to obtain the same luminance and chromaticity coordinates as in
Example 6. When the multi-color light emission apparatus was
allowed to stand under a nitrogen stream for two weeks, it
maintained uniform light emission without changes in luminance and
chromaticity coordinate and also without dark spots as
deterioration of the device progressed. Also, the angle of view
defined by the range in which leakage of light (mono-chromatic
light) emitted from the organic electroluminescence device was not
confirmed was .+-.55.degree., which was a practical level.
Example 8
A photocurable resist containing carbon black (CK 2000,
manufactured by Fuji Hunt Electronics Technology Co., Ltd.) was
applied by spin-coating to a glass substrate (7059, manufactured by
Corning Co., Ltd.) of 100 mm.times.100 mm.times.1.1 mm (thickness)
as a transparent support substrate, which was baked at 80.degree.
C. Then, an oxygen shielding film of polyvinyl alcohol(CP,
manufactured by Fuji Hunt Electronics Technology Co., Ltd.) was
formed on the substrate by spin-coating, and was baked at
80.degree. C. Next, the resulting substrate was placed on a
proximity type exposure machine. The substrate was then irradiated
with light at a dose of 100 mJ/cm.sup.2 (365 nm) using a mask
capable of transferring a stripe pattern of 0.3 mm lines and 1.2 mm
gaps. The resist on the substrate was developed using aqueous 1N
sodium carbonate solution and post-baked at 200.degree. C. to
provide a black matrix.
A photocurable resist containing copper phthalocyanine (CB 2000,
manufactured by Fuji Hunt Electronics Technology Co., Ltd.) was
applied to the substrate by spin-coating and was baked at
80.degree. C. Then, an oxygen shielding film of polyvinyl alcohol
(CP, manufactured by Fuji Hunt Electronics Technology Co., Ltd.)
was formed on the substrate by spin-coating and was baked at
80.degree. C. Next, the substrate was placed on a proximity type
exposure machine. The substrate was then irradiated with light at a
dose of 100 mJ/cm.sup.2 (365 nm) using a mask capable of
transferring a stripe pattern of 1.4 mm lines and 3.1 mm gaps after
aligning the substrate so that the pattern was embedded in gaps of
the black matrix. The resist on the substrate was developed using
aqueous 1N sodium carbonate solution and post-baked at 200.degree.
C. to provide a blue color filter.
Fluorescent layers A and B were printed by screen printing on
portions other than the blue color filter of the substrate provided
with the black matrix and the blue color filter under the same
conditions as in Example 1 after alignment with the gaps of the
black matrix. Then, the same glass plate as in Example 1,
specifically, a glass plate with a thickness of 50 .mu.m, which was
provided with a film of ITO (anode), was applied to the above
substrate to form an ITO pattern.
Next, this substrate was washed with IPA and further irradiated
with UV light. Then, the substrate was secured to a substrate
holder of a vapor deposition unit (manufactured by ULVAC
Corporation). As materials for vapor deposition, MTDATA and NPD for
a positive hole injecting layer, DPVBi for an emitting material,
DPAVB for a dopant, and Alq for an electron injecting layer were
placed in a resistance heating molybdenum boat. Ag as a second
metal for an electrode (cathode) was attached to a tungsten
filament, and Mg as an electron injecting metal for an electrode
(cathode) was attached to the molybdenum boat.
After that, the pressure in the vacuum vessel was reduced to
5.times.10.sup.-7 torr and the above materials were sequentially
laminated in the following order. A vacuum was maintained during
the steps between the step of forming the positive hole injecting
layer and the step of forming the cathode by one evacuating
operation. First, a positive hole injecting layer was formed by
depositing MTDATA at a vapor deposition rate of 0.1-0.3 nm/s to a
film thickness of 200 nm and also depositing NPD at a vapor
deposition rate of 0.1-0.3 nm/s to a film thickness of 20 nm. Then,
an emitting layer was formed by depositing DPVBi at a vapor
deposition rate of 0.1-0.3 nm/s and also depositing DPAVB at a
vapor deposition rate of 0.05 nm/s to a total film thickness of 40
nm (the proportion by weight of dopant to host material was from
1.2 to 1.6). Then, an electron injecting layer was formed by
depositing Alq at a vapor deposition rate of 0.1-0.3 nm/s to a film
thickness of 20 nm. Finally, Mg and Ag were simultaneously
vapor-deposited as the cathode at vapor deposition rates of 1.3-1.4
nm/s and 0.1 nm/s respectively to a film thickness of 200 nm
through a mask capable of transferring a stripe pattern of 4 mm
lines and 0.5 mm gaps which is perpendicular to the stripe pattern
of the ITO anode.
A multi-color light emission apparatus composed of the organic EL
device was manufactured in this manner as shown in FIG. 13. When a
d.c. voltage of 8 V was applied between the anode and the cathode
of the multi-color light emission apparatus, the crossed portions
of the anodes and cathodes emitted light. The luminance of the
light viewed from the blue color filter was 35 cd/m.sup.2. The CIE
chromaticity coordinates (JIS Z 8701) were as follows: x=0.14,
y=0.12. Light of a blue color was detected.
On the other hand, the luminance of the light viewed from the
fluorescent layer A was 120 cd/m.sup.2 and the CIE chromaticity
coordinates were as follows: x=0.28, y=0.62. Light of a yellowish
green color was detected.
Also, the luminance of the light viewed from the fluorescent layer
B was 30 cd/m.sup.2 and the CIE chromaticity coordinates were as
follows: x=0.60, y=0.31. Light of a red color was detected.
The multi-color light emission apparatus manufactured in the above
manner was allowed to stand under a nitrogen stream for two weeks.
As a result, the multi-color light emission apparatus maintained
uniform light emission without changes in luminance and
chromaticity coordinate and also without dark spots appearing as
deterioration of the device progressed. Also, the angle of view
defined by the range in which color mixing was not confirmed when
mono-chromatic light was emitted was .+-.70.degree., which was a
practical level.
Example 9
A methacrylate type photocurable resin (V259PA, manufactured by
Nippon Steel Chemical Co., Ltd.) was applied, by spin-coating, to
the substrate provided with the fluorescent layers A and B, which
was prepared in Example 6. After baking at 80.degree. C., the
substrate was irradiated with UV light at a dose of 300 mJ/cm.sup.2
(365 nm). Then, the substrate was baked at 160.degree. C. to
laminate a transparent protective layer with a thickness of 5
.mu.m.
Next, a silicon oxide film as as insulating inorganic oxide layer
with a thickness of 0.01 .mu.m was laminated over the entire
substrate heated at 160.degree. C. using a sputtering apparatus.
Then, a film of ITO (anode) with a thickness of 0.12 .mu.m and a
surface resistance of 20 .OMEGA./.quadrature. was formed on the
substrate using a sputtering apparatus, while the substrate was
heated at 160.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to prepare a multi-color
light emission apparatus composed of the organic EL device shown in
FIG. 12. This multi-color light emission apparatus was allowed to
emit light to obtain the same luminance and chromaticity
coordinates as in those in Example 6. When the multi-color light
emission apparatus was allowed to stand under a nitrogen stream for
two weeks, the multi-color light emission apparatus maintained
uniform light emission with almost no changes in luminance and
chromaticity coordinates and also with few dark spots appearing as
deterioration of the device progressed. Also, the angle of view
defined by the range in which leakage of light (mono-chromatic
light) emitted from the organic electroluminescence device was not
confirmed was .+-.90.degree., which was a practical level.
The water content of the silicon oxide film with a thickness of
0.01 .mu.m was 0.1% by weight or less and the gas permeability of
the silicon oxide film for aqueous vapor and for oxygen was
10.sup.-13 cccm/cm.sup.2 scmHg or less.
Example 10
An aluminum oxide film as an insulating inorganic oxide layer with
a thickness of 0.01 .mu.m was laminated over the entire substrate
provided with the fluorescent layers A and B, which was prepared in
Example 6, using a sputtering apparatus while heating the substrate
at 160.degree. C. Then, a solid film of ITO with a thickness of
0.12 .mu.m and a surface resistance of 20 .OMEGA./.quadrature. was
formed on the substrate using a sputtering apparatus, while the
substrate was heated at 160.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to prepare a multi-color
light emission apparatus composed of the organic EL device shown in
FIG. 9. This multi-color light emission apparatus was allowed to
emit light to obtain the same luminance and chromaticity
coordinates as in those in Example 6. When the multi-color light
emission apparatus was allowed to stand under a nitrogen stream for
two weeks, the multi-color light emission apparatus maintained
uniform light emission with almost no changes in luminance and
chromaticity coordinate and also with few dark spots appearing as
deterioration of the device progressed. Also, the angle of view
defined by the range in which leakage of light (mono-chromatic
light) emitted from the organic electroluminescence device was not
confirmed was .+-.90.degree., which was a practical level.
The water content of the aluminum oxide film with a thickness of
0.01 .mu.m was 0.1% by weight or less and the gas permeability of
the aluminum oxide film for aqueous vapor and for oxygen was
10.sup.-13 cccm/cm.sup.2 scmHg or less.
Example 11
A titanium oxide film as an insulating inorganic oxide layer with a
thickness of 0.01 .mu.m was laminated by sputtering over the entire
substrate provided with the fluorescent layers A and B, which was
prepared in Example 6, while heating the substrate at 160.degree.
C. Then, a solid film of ITO with a thickness of 0.12 .mu.m and a
surface resistance of 20 .OMEGA./.quadrature. was formed on the
substrate using a sputtering apparatus, while the substrate was
heated at 160.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to prepare a multi-color
light emission apparatus composed of the organic EL device shown in
FIG. 9. This multi-color light emission apparatus was allowed to
emit light to obtain the same luminance and chromaticity
coordinates as in those in Example 6. When the multi-color light
emission apparatus was allowed to stand under a nitrogen stream for
two weeks, the multi-color light emission apparatus maintained
uniform light emission with almost no changes in luminance and
chromaticity coordinates and also with few dark spots appearing as
deterioration of the device progressed. Also, the angle of view
defined by the range in which leakage of light (mono-chromatic
light) emitted from the organic electroluminescence device was not
confirmed was .+-.90.degree., which was a practical level.
The water content of the titanium oxide film with a thickness of
0.01 .mu.m was 0.1% by weight or less and the gas permeability of
the titanium oxide film for aqueous vapor and for oxygen was
10.sup.-13 cccm/cm.sup.2 scmHg or less.
Example 12
A photocurable transparent adhesive of a methacrylate type oligomer
(3102, manufactured by 3-Bond corp.) was applied, by casting, to
the substrate prepared in Example 6, in which the protective layer
was laminated on the fluorescent layers A and B. The glass surface
of a glass substrate (soda-lime glass) of 100 mm.times.100
mm.times.50 .mu.m thickness as an insulating inorganic oxide layer
on which a titanium oxide film with a thickness of 0.05 .mu.m and a
film of a transparent electrode of ITO (anode) with a thickness of
0.12 .mu.m were completely formed in order was applied to the
substrate. The substrate was irradiated with UV rays through the
surface of the ITO at a dose of 3,000 mJ/cm.sup.2 (365 nm),
followed by baking at 80.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to prepare a multi-color
light emission apparatus composed of the organic EL device shown in
FIG. 14. This multi-color light emission apparatus was allowed to
emit light to obtain the same luminance and chromaticity coordinate
as in those in Example 6. When the multi-color light emission
apparatus was allowed to stand under a nitrogen stream for two
weeks, the multi-color light emission apparatus maintained uniform
light emission with almost no changes in luminance and chromaticity
coordinate and also with few dark spots appearing as deterioration
of the device progressed. Also, the angle of view defined by the
range in which leakage of light (mono-chromatic light) emitted from
the organic electroluminescence device was not confirmed was
.+-.60.degree., which was a practical level.
The water content of the glass substrate with a thickness of 50
.mu.m, on which the titanium oxide film with a thickness of 0.01
.mu.m was formed, in this example, was 0.1% by weight or less and
the gas permeability of the glass substrate, on which titanium
oxide film was formed, for aqueous vapor and for oxygen was
10.sup.-13 cccm/cm.sup.2 scmHg or less.
Comparative Example 3 (in the case of no provision for the
inorganic oxide layer)
A methacrylate type photocurable resin (V259PA, manufactured by
Nippon Steel Chemical Co., Ltd.) was applied, by spin-coating, to
the substrate provided with the fluorescent layers A and B, which
was prepared in Example 6. After baking at 80.degree. C., the
substrate was irradiated with UV light at a dose of 300 mJ/cm.sup.2
(365 nm). Then, the substrate was baked at 160.degree. C. to
laminate a transparent protective layer with a thickness of 5
.mu.m.
Next, a film of ITO (anode) with a thickness of 0.12 .mu.m and a
surface resistance of 20 .OMEGA./.quadrature. was formed on the
substrate using a sputtering apparatus, while the substrate was
heated at 160.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to prepare a multi-color
light emission apparatus composed of the organic EL device shown in
FIG. 15. This multi-color light emission apparatus was allowed to
emit light to obtain the same luminance and chromaticity as in
those in Example 6. However, when the multi-color light emission
apparatus was allowed to stand under a nitrogen stream for two
weeks, the luminance viewed from the portion lacking the
fluorescent layer under the same conditions as in Example 6
decreased to 5 cd/cm.sup.2 and many dark points as deterioration of
the device progressed, exhibiting a clear problem.
The total content of water contained in the protective layer was
1.2% by weight and the gas permeability of the protective layer for
aqueous vapor and for oxygen was 10.sup.-13 cccm/cm.sup.2 scmHg or
more.
Comparative Example 4 (in the case where the thickness of the
inorganic oxide layer was 0.005 .mu.m)
A methacrylate type photocurable resin (V259PA, manufactured
byNippon Steel Chemical Co., Ltd.) was applied, by spin-coating, to
the substrate provided with the fluorescent layers A and B, which
was prepared in Example 6. After baking at 80.degree. C., the
substrate was irradiated with UV light at a dose of 300 mJ/cm.sup.2
(365 nm). Then, the substrate was baked at 160.degree. C. to
laminate a transparent protective film with a thickness of 5
.mu.m.
Next, using a sputtering apparatus, a silicon oxide film as an
insulating inorganic oxide layer with a thickness of 0.005 .mu.m
was laminated over the entire substrate heated at 160.degree. C.
and a solid film of ITO with a thickness of 0.12 .mu.m and a
surface resistance of 20 .OMEGA./.quadrature. was formed over the
entire substrate using a sputtering apparatus, while the substrate
was heated at 160.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to prepare a multi-color
light emission apparatus composed of the organic EL device. This
multi-color light emission apparatus was allowed to emit light to
obtain the same luminance and chromaticity as in Example 6.
However, when the multi-color light emission apparatus was allowed
to stand under a nitrogen stream for two weeks, the luminance
viewed from the portion lacking the fluorescent layer under the
same conditions as in Example 6 decreased to 20 cd/cm.sup.2 and
many dark spots as deterioration of the device progressed,
exhibiting a clear problem.
The water content of the silicon oxide film with a thickness of
0.005 .mu.m was 0.1% by weight or less. However, the gas
permeability of the silicon oxide film with a thickness of 0.005
.mu.m for aqueous vapor and for oxygen was 10.sup.-13 cccm/cm.sup.2
scmHg or more.
Comparative Example 5 (in the case where the thickness of the
inorganic oxide layer (plate glass) was 300 .mu.m)
The glass surface of a glass plate (borosilicate glass) of 100
mm.times.100 mm.times.300 .mu.m thickness as an insulating
inorganic oxide layer on which a solid film of ITO (anode) with a
thickness of 0.12 .mu.m and a surface resistance of 20
.OMEGA./.quadrature. was formed was applied to the substrate
prepared in Example 6, on which the patterns of the fluorescent
layers A and B, the protective layer, and the adhesive layer were
subsequently laminated. The substrate was irradiated with UV rays
through the ITO surface at a dose of 3,000 mJ/cm.sup.2 (365 nm),
followed by baking at 80.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to prepare a multi-color
light emission apparatus composed of the organic EL device. This
multi-color light emission apparatus was allowed to emit light to
obtain the same luminance and chromaticity as in Example 6. When
the multi-color light emission apparatus was allowed to stand under
a nitrogen stream for two weeks, the multi-color light emission
apparatus maintained uniform light emission with almost no changes
in luminance and chromaticity coordinates and also with few dark
points appearing with the progress in deterioration of the device.
However, the angle of view defined by the range in which leakage of
light (mono-chromatic light) emitted from the organic EL device was
not confirmed was .+-.30.degree.. There were portions (angles)
where light of a color differing from the emitted color was viewed
in a normal sight range, exhibiting a practical problem.
Comparative Example 6 (in the case of forming the protective layer
(flat layer) using a sol-gel glass method)
The substrate produced in Example 6, which was provided with the
patterns of the fluorescent layers A and B, was dipped into a mixed
solution consisting of 10% by weight of tetraethoxysilane
(Si(OC.sub.2 H.sub.5).sub.4) and water/ethanol (ratio by volume:
1:2) containing 1% by weight of hydrochloric acid.
The substrate was slowly lifted to produce a substrate in which the
fluorescent layers A and B were dip-coated with silicon oxide
(SiO.sub.2) sol.
The substrate was then heated at 400.degree. C. so that silicon
oxide was allowed to gel and thereby a glass-like protective layer
was laminated on the fluorescent layers A and B. However, it was
confirmed that the patterns of the fluorescent layers A and B were
blackened (carbonized) to show deterioration in these layers.
Because of this, the substrate was heated at 160.degree. C. so that
silicon oxide was allowed to gel and thereby a glass-like
protective layer with a thickness of 0.2 .mu.m was laminated on the
fluorescent layers A and B.
Next, a film of ITO (anode) with a thickness of 0.12 .mu.m and a
surface resistance of 20 .OMEGA./.quadrature. was formed on the
entire substrate using a sputtering apparatus, while the substrate
was heated at 160.degree. C.
Then, the ITO was patterned and an organic EL device was formed
under the same conditions as in Example 6 to provide a multi-color
light emission apparatus composed of the organic EL device shown in
FIG. 15. This multi-color light emission apparatus was allowed to
emit light to obtain the same luminance and chromaticity as in
Example 6. However, when the multi-color light emission apparatus
was allowed to stand under a nitrogen stream for two weeks, the
luminance viewed from the portion lacking the fluorescent layer
under the same conditions as in Example 6 decreased to 5
cd/cm.sup.2 and many dark spots appeared as deterioration of the
device progressed, exhibiting a clear problem.
The water content contained in the sol-gel silicon oxide film with
a thickness of 0.2 .mu.m was 1.5% by weight. Also, the gas
permeability of the sol-gel silicon oxide film to aqueous vapor and
to oxygen was 10.sup.-13 cccm/cm.sup.2 scmHg or more, showing that
the protective layer produced by the sol-gel method was
inappropriate.
INDUSTRIAL APPLICABILITY
As is clear from the above explanations, the present invention can
provide a multi-color light emission apparatus using an organic EL
device having an excellent light emission life and excellent
characteristics in the angle of view. Also, the present invention
can provide a process for manufacturing the multi-color light
emission apparatus in a stable and efficient manner.
Accordingly, the present invention can be preferably applied for
thin type multi-color or full color displays of various emission
types.
* * * * *